diff --git a/.eslintrc.js b/.eslintrc.js
index b427c9986f679f..49a810249146d7 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -44,10 +44,7 @@ module.exports = {
   parserOptions: {
     babelOptions: {
       plugins: [
-        [
-          Module._findPath('@babel/plugin-syntax-import-attributes'),
-          { deprecatedAssertSyntax: true },
-        ],
+        Module._findPath('@babel/plugin-syntax-import-attributes'),
       ],
     },
     requireConfigFile: false,
diff --git a/deps/v8/include/v8-script.h b/deps/v8/include/v8-script.h
index 5644a3bb70c6b1..91b0a3d3e73378 100644
--- a/deps/v8/include/v8-script.h
+++ b/deps/v8/include/v8-script.h
@@ -128,10 +128,9 @@ class V8_EXPORT ModuleRequest : public Data {
    *
    * All assertions present in the module request will be supplied in this
    * list, regardless of whether they are supported by the host. Per
-   * https://tc39.es/proposal-import-assertions/#sec-hostgetsupportedimportassertions,
-   * hosts are expected to ignore assertions that they do not support (as
-   * opposed to, for example, triggering an error if an unsupported assertion is
-   * present).
+   * https://tc39.es/proposal-import-attributes/#sec-hostgetsupportedimportattributes,
+   * hosts are expected to throw for assertions that they do not support (as
+   * opposed to, for example, ignoring them).
    */
   Local<FixedArray> GetImportAssertions() const;
 
diff --git a/deps/v8/src/execution/isolate.cc b/deps/v8/src/execution/isolate.cc
index e5dba75764f6a9..d9bb966fe64af1 100644
--- a/deps/v8/src/execution/isolate.cc
+++ b/deps/v8/src/execution/isolate.cc
@@ -4726,7 +4726,7 @@ MaybeHandle<FixedArray> Isolate::GetImportAssertionsFromArgument(
 
   // The parser shouldn't have allowed the second argument to import() if
   // the flag wasn't enabled.
-  DCHECK(FLAG_harmony_import_assertions);
+  DCHECK(FLAG_harmony_import_assertions || FLAG_harmony_import_attributes);
 
   if (!import_assertions_argument->IsJSReceiver()) {
     this->Throw(
@@ -4736,18 +4736,35 @@ MaybeHandle<FixedArray> Isolate::GetImportAssertionsFromArgument(
 
   Handle<JSReceiver> import_assertions_argument_receiver =
       Handle<JSReceiver>::cast(import_assertions_argument);
-  Handle<Name> key = factory()->assert_string();
 
   Handle<Object> import_assertions_object;
-  if (!JSReceiver::GetProperty(this, import_assertions_argument_receiver, key)
-           .ToHandle(&import_assertions_object)) {
-    // This can happen if the property has a getter function that throws
-    // an error.
-    return MaybeHandle<FixedArray>();
+
+  if (FLAG_harmony_import_attributes) {
+    Handle<Name> with_key = factory()->with_string();
+    if (!JSReceiver::GetProperty(this, import_assertions_argument_receiver,
+                                 with_key)
+             .ToHandle(&import_assertions_object)) {
+      // This can happen if the property has a getter function that throws
+      // an error.
+      return MaybeHandle<FixedArray>();
+    }
   }
 
-  // If there is no 'assert' option in the options bag, it's not an error. Just
-  // do the import() as if no assertions were provided.
+  if (FLAG_harmony_import_assertions &&
+      (!FLAG_harmony_import_attributes ||
+       import_assertions_object->IsUndefined())) {
+    Handle<Name> assert_key = factory()->assert_string();
+    if (!JSReceiver::GetProperty(this, import_assertions_argument_receiver,
+                                 assert_key)
+             .ToHandle(&import_assertions_object)) {
+      // This can happen if the property has a getter function that throws
+      // an error.
+      return MaybeHandle<FixedArray>();
+    }
+  }
+
+  // If there is no 'with' or 'assert' option in the options bag, it's not an
+  // error. Just do the import() as if no assertions were provided.
   if (import_assertions_object->IsUndefined()) return import_assertions_array;
 
   if (!import_assertions_object->IsJSReceiver()) {
@@ -4769,6 +4786,8 @@ MaybeHandle<FixedArray> Isolate::GetImportAssertionsFromArgument(
     return MaybeHandle<FixedArray>();
   }
 
+  bool has_non_string_attribute = false;
+
   // The assertions will be passed to the host in the form: [key1,
   // value1, key2, value2, ...].
   constexpr size_t kAssertionEntrySizeForDynamicImport = 2;
@@ -4786,9 +4805,7 @@ MaybeHandle<FixedArray> Isolate::GetImportAssertionsFromArgument(
     }
 
     if (!assertion_value->IsString()) {
-      this->Throw(*factory()->NewTypeError(
-          MessageTemplate::kNonStringImportAssertionValue));
-      return MaybeHandle<FixedArray>();
+      has_non_string_attribute = true;
     }
 
     import_assertions_array->set((i * kAssertionEntrySizeForDynamicImport),
@@ -4797,6 +4814,12 @@ MaybeHandle<FixedArray> Isolate::GetImportAssertionsFromArgument(
                                  *assertion_value);
   }
 
+  if (has_non_string_attribute) {
+    this->Throw(*factory()->NewTypeError(
+        MessageTemplate::kNonStringImportAssertionValue));
+    return MaybeHandle<FixedArray>();
+  }
+
   return import_assertions_array;
 }
 
diff --git a/deps/v8/src/flags/flag-definitions.h b/deps/v8/src/flags/flag-definitions.h
index f02ef309d69e45..48dc37118c5482 100644
--- a/deps/v8/src/flags/flag-definitions.h
+++ b/deps/v8/src/flags/flag-definitions.h
@@ -300,6 +300,7 @@ DEFINE_BOOL(harmony_shipping, true, "enable all shipped harmony features")
 
 // Features that are still work in progress (behind individual flags).
 #define HARMONY_INPROGRESS_BASE(V)                                             \
+  V(harmony_import_attributes, "harmony import attributes")                    \
   V(harmony_weak_refs_with_cleanup_some,                                       \
     "harmony weak references with FinalizationRegistry.prototype.cleanupSome") \
   V(harmony_import_assertions, "harmony import assertions")                    \
diff --git a/deps/v8/src/init/bootstrapper.cc b/deps/v8/src/init/bootstrapper.cc
index d4c4122c22f4d7..ead61d6222907f 100644
--- a/deps/v8/src/init/bootstrapper.cc
+++ b/deps/v8/src/init/bootstrapper.cc
@@ -4482,6 +4482,7 @@ void Genesis::InitializeConsole(Handle<JSObject> extras_binding) {
   void Genesis::InitializeGlobal_##id() {}
 
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_import_assertions)
+EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_import_attributes)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_private_brand_checks)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_class_static_blocks)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_error_cause)
diff --git a/deps/v8/src/init/heap-symbols.h b/deps/v8/src/init/heap-symbols.h
index 8cd69613a678c3..cfff76beb4aaed 100644
--- a/deps/v8/src/init/heap-symbols.h
+++ b/deps/v8/src/init/heap-symbols.h
@@ -432,6 +432,7 @@
   V(_, week_string, "week")                                           \
   V(_, weeks_string, "weeks")                                         \
   V(_, weekOfYear_string, "weekOfYear")                               \
+  V(_, with_string, "with")                                           \
   V(_, word_string, "word")                                           \
   V(_, writable_string, "writable")                                   \
   V(_, yearMonthFromFields_string, "yearMonthFromFields")             \
diff --git a/deps/v8/src/parsing/parser-base.h b/deps/v8/src/parsing/parser-base.h
index cfa91e446f82e9..30dff440f6522b 100644
--- a/deps/v8/src/parsing/parser-base.h
+++ b/deps/v8/src/parsing/parser-base.h
@@ -3725,7 +3725,9 @@ ParserBase<Impl>::ParseImportExpressions() {
   AcceptINScope scope(this, true);
   ExpressionT specifier = ParseAssignmentExpressionCoverGrammar();
 
-  if (FLAG_harmony_import_assertions && Check(Token::COMMA)) {
+  if ((FLAG_harmony_import_assertions ||
+       FLAG_harmony_import_attributes) &&
+      Check(Token::COMMA)) {
     if (Check(Token::RPAREN)) {
       // A trailing comma allowed after the specifier.
       return factory()->NewImportCallExpression(specifier, pos);
diff --git a/deps/v8/src/parsing/parser.cc b/deps/v8/src/parsing/parser.cc
index 9789909456ee5e..4a60275a546d30 100644
--- a/deps/v8/src/parsing/parser.cc
+++ b/deps/v8/src/parsing/parser.cc
@@ -1344,39 +1344,42 @@ ZonePtrList<const Parser::NamedImport>* Parser::ParseNamedImports(int pos) {
 }
 
 ImportAssertions* Parser::ParseImportAssertClause() {
-  // AssertClause :
-  //    assert '{' '}'
-  //    assert '{' AssertEntries '}'
+  // WithClause :
+  //    with '{' '}'
+  //    with '{' WithEntries ','? '}'
 
-  // AssertEntries :
-  //    IdentifierName: AssertionKey
-  //    IdentifierName: AssertionKey , AssertEntries
+  // WithEntries :
+  //    LiteralPropertyName
+  //    LiteralPropertyName ':' StringLiteral , WithEntries
 
-  // AssertionKey :
-  //     IdentifierName
-  //     StringLiteral
+  // (DEPRECATED)
+  // AssertClause :
+  //    assert '{' '}'
+  //    assert '{' WithEntries ','? '}'
 
   auto import_assertions = zone()->New<ImportAssertions>(zone());
 
-  if (!FLAG_harmony_import_assertions) {
-    return import_assertions;
-  }
+  if (FLAG_harmony_import_attributes && Check(Token::WITH)) {
+    // 'with' keyword consumed
+  } else if (FLAG_harmony_import_assertions &&
+             !scanner()->HasLineTerminatorBeforeNext() &&
+             CheckContextualKeyword(ast_value_factory()->assert_string())) {
+    // The 'assert' contextual keyword is deprecated in favor of 'with', and we
+    // need to investigate feasibility of unshipping.
+    //
+    // TODO(v8:13856): Remove once decision is made to unship 'assert' or keep.
 
-  // Assert clause is optional, and cannot be preceded by a LineTerminator.
-  if (scanner()->HasLineTerminatorBeforeNext() ||
-      !CheckContextualKeyword(ast_value_factory()->assert_string())) {
+    // NOTE(Node.js): Commented out to avoid backporting this use counter to Node.js 18
+    // ++use_counts_[v8::Isolate::kImportAssertionDeprecatedSyntax];
+  } else {
     return import_assertions;
   }
 
   Expect(Token::LBRACE);
 
   while (peek() != Token::RBRACE) {
-    const AstRawString* attribute_key = nullptr;
-    if (Check(Token::STRING)) {
-      attribute_key = GetSymbol();
-    } else {
-      attribute_key = ParsePropertyName();
-    }
+    const AstRawString* attribute_key =
+        Check(Token::STRING) ? GetSymbol() : ParsePropertyName();
 
     Scanner::Location location = scanner()->location();
 
diff --git a/deps/v8/test/mjsunit/harmony/modules-import-attributes-1.mjs b/deps/v8/test/mjsunit/harmony/modules-import-attributes-1.mjs
new file mode 100644
index 00000000000000..3cf6bac870b80f
--- /dev/null
+++ b/deps/v8/test/mjsunit/harmony/modules-import-attributes-1.mjs
@@ -0,0 +1,9 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --harmony-import-attributes
+
+import { life } from 'modules-skip-1.mjs' with { };
+
+assertEquals(42, life());
diff --git a/deps/v8/test/mjsunit/harmony/modules-import-attributes-2.mjs b/deps/v8/test/mjsunit/harmony/modules-import-attributes-2.mjs
new file mode 100644
index 00000000000000..63f5859ca0f1d0
--- /dev/null
+++ b/deps/v8/test/mjsunit/harmony/modules-import-attributes-2.mjs
@@ -0,0 +1,9 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --harmony-import-attributes
+
+import json from 'modules-skip-1.json' with { type: 'json' };
+
+assertEquals(42, json.life);
diff --git a/deps/v8/test/mjsunit/harmony/modules-import-attributes-3.mjs b/deps/v8/test/mjsunit/harmony/modules-import-attributes-3.mjs
new file mode 100644
index 00000000000000..34db1852367c19
--- /dev/null
+++ b/deps/v8/test/mjsunit/harmony/modules-import-attributes-3.mjs
@@ -0,0 +1,9 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --harmony-import-attributes
+
+import {life} from 'modules-skip-imports-json-1.mjs';
+
+assertEquals(42, life());
diff --git a/deps/v8/test/mjsunit/harmony/modules-import-attributes-4.mjs b/deps/v8/test/mjsunit/harmony/modules-import-attributes-4.mjs
new file mode 100644
index 00000000000000..66bdc11c359ed4
--- /dev/null
+++ b/deps/v8/test/mjsunit/harmony/modules-import-attributes-4.mjs
@@ -0,0 +1,9 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --harmony-import-attributes
+
+import json from 'modules-skip-1.json' with { type: 'json', notARealAssertion: 'value'};
+
+assertEquals(42, json.life);
diff --git a/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-1.mjs b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-1.mjs
new file mode 100644
index 00000000000000..644fc96a6e2111
--- /dev/null
+++ b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-1.mjs
@@ -0,0 +1,12 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax --harmony-import-attributes
+
+var life;
+import('modules-skip-1.mjs', { }).then(namespace => life = namespace.life());
+
+%PerformMicrotaskCheckpoint();
+
+assertEquals(42, life);
diff --git a/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-10.mjs b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-10.mjs
new file mode 100644
index 00000000000000..972fbed24bfff2
--- /dev/null
+++ b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-10.mjs
@@ -0,0 +1,19 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax --harmony-import-attributes
+
+var result1;
+var result2;
+import('modules-skip-1.json', { get with() { throw 'bad \'with\' getter!'; } }).then(
+    () => assertUnreachable('Should have failed due to throwing getter'),
+    error => result1 = error);
+import('modules-skip-1.json', { with: { get assertionKey() { throw 'bad \'assertionKey\' getter!'; } } }).then(
+    () => assertUnreachable('Should have failed due to throwing getter'),
+    error => result2 = error);
+
+%PerformMicrotaskCheckpoint();
+
+assertEquals('bad \'with\' getter!', result1);
+assertEquals('bad \'assertionKey\' getter!', result2);
\ No newline at end of file
diff --git a/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-11.mjs b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-11.mjs
new file mode 100644
index 00000000000000..c39a5f9d4e2e06
--- /dev/null
+++ b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-11.mjs
@@ -0,0 +1,19 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax --harmony-import-attributes --harmony-top-level-await
+
+var life1;
+var life2;
+import('modules-skip-1.json', { with: { type: 'json' } }).then(
+    namespace => life1 = namespace.default.life);
+
+// Try loading the same module a second time.
+import('modules-skip-1.json', { with: { type: 'json' } }).then(
+    namespace => life2 = namespace.default.life);
+
+%PerformMicrotaskCheckpoint();
+
+assertEquals(42, life1);
+assertEquals(42, life2);
diff --git a/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-12.mjs b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-12.mjs
new file mode 100644
index 00000000000000..1d8fb21a502237
--- /dev/null
+++ b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-12.mjs
@@ -0,0 +1,26 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax --harmony-import-attributes
+
+let result1;
+let result2;
+
+let badAssertProxy1 = new Proxy({}, { ownKeys() { throw "bad ownKeys!"; } });
+import('./modules-skip-1.mjs', { with: badAssertProxy1 }).then(
+    () => assertUnreachable('Should have failed due to throwing ownKeys'),
+    error => result1 = error);
+
+let badAssertProxy2 = new Proxy(
+    {foo: "bar"},
+    { getOwnPropertyDescriptor() { throw "bad getOwnPropertyDescriptor!"; } });
+import('./modules-skip-1.mjs', { with: badAssertProxy2 }).then(
+    () => assertUnreachable(
+        'Should have failed due to throwing getOwnPropertyDescriptor'),
+    error => result2 = error);
+
+%PerformMicrotaskCheckpoint();
+
+assertEquals('bad ownKeys!', result1);
+assertEquals('bad getOwnPropertyDescriptor!', result2);
\ No newline at end of file
diff --git a/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-13.mjs b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-13.mjs
new file mode 100644
index 00000000000000..6e23c07c281db1
--- /dev/null
+++ b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-13.mjs
@@ -0,0 +1,26 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax --harmony-import-attributes
+
+let getters = 0;
+let result;
+
+import('./modules-skip-1.mjs', { with: {
+    get attr1() {
+        getters++;
+        return {};
+    },
+    get attr2() {
+        getters++;
+        return {};
+    },
+} }).then(
+    () => assertUnreachable('Should have failed due to invalid attributes values'),
+    error => result = error);
+
+%PerformMicrotaskCheckpoint();
+
+assertEquals(2, getters);
+assertInstanceof(result, TypeError);
diff --git a/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-2.mjs b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-2.mjs
new file mode 100644
index 00000000000000..b8e59fb0bfe9c3
--- /dev/null
+++ b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-2.mjs
@@ -0,0 +1,13 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax --harmony-import-attributes
+
+var life;
+import('modules-skip-1.mjs', { with: { } }).then(
+    namespace => life = namespace.life());
+
+%PerformMicrotaskCheckpoint();
+
+assertEquals(42, life);
diff --git a/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-3.mjs b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-3.mjs
new file mode 100644
index 00000000000000..da570eb2836edd
--- /dev/null
+++ b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-3.mjs
@@ -0,0 +1,13 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax --harmony-import-attributes
+
+var life;
+import('modules-skip-1.json', { with: { type: 'json' } }).then(
+    namespace => life = namespace.default.life);
+
+%PerformMicrotaskCheckpoint();
+
+assertEquals(42, life);
diff --git a/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-4.mjs b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-4.mjs
new file mode 100644
index 00000000000000..fff6fe2bbef84c
--- /dev/null
+++ b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-4.mjs
@@ -0,0 +1,14 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax --harmony-import-attributes
+
+var result;
+import('modules-skip-1.json', { with: { type: 'notARealType' } }).then(
+    () => assertUnreachable('Should have failed due to bad module type'),
+    error => result = error.message);
+
+%PerformMicrotaskCheckpoint();
+
+assertEquals('Invalid module type was asserted', result);
diff --git a/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-5.mjs b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-5.mjs
new file mode 100644
index 00000000000000..cdb1567c330764
--- /dev/null
+++ b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-5.mjs
@@ -0,0 +1,12 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax --harmony-import-attributes
+
+var life;
+import('modules-skip-imports-json-1.mjs',).then(namespace => life = namespace.life());
+
+%PerformMicrotaskCheckpoint();
+
+assertEquals(42, life);
diff --git a/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-6.mjs b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-6.mjs
new file mode 100644
index 00000000000000..ad84e3edd5ffe1
--- /dev/null
+++ b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-6.mjs
@@ -0,0 +1,18 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax --harmony-import-attributes
+
+var life;
+import('modules-skip-1.json', { with: { type: 'json', notARealAssertion: 'value' } }).then(
+    namespace => life = namespace.default.life);
+
+var life2;
+import('modules-skip-1.json', { with: { 0: 'value', type: 'json' } }).then(
+    namespace => life2 = namespace.default.life);
+
+%PerformMicrotaskCheckpoint();
+
+assertEquals(42, life);
+assertEquals(42, life2);
diff --git a/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-7.mjs b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-7.mjs
new file mode 100644
index 00000000000000..530d833cce5a4d
--- /dev/null
+++ b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-7.mjs
@@ -0,0 +1,63 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax --harmony-import-attributes
+
+var result1;
+var result2;
+var result3;
+var result4;
+var result5;
+var result6;
+var result7;
+var result8;
+var result9;
+var result10;
+import('modules-skip-1.json', null).then(
+    () => assertUnreachable('Should have failed due to non-object parameter'),
+    error => result1 = error.message);
+import('modules-skip-1.json', 7).then(
+    () => assertUnreachable('Should have failed due to non-object parameter'),
+    error => result2 = error.message);
+import('modules-skip-1.json', 'string').then(
+        () => assertUnreachable('Should have failed due to non-object parameter'),
+        error => result3 = error.message);
+import('modules-skip-1.json', { with: null}).then(
+    () => assertUnreachable('Should have failed due to bad with object'),
+    error => result4 = error.message);
+import('modules-skip-1.json', { with: 7}).then(
+    () => assertUnreachable('Should have failed due to bad with object'),
+    error => result5 = error.message);
+import('modules-skip-1.json', { with: 'string'}).then(
+    () => assertUnreachable('Should have failed due to bad with object'),
+    error => result6 = error.message);
+import('modules-skip-1.json', { with: { a: null }}).then(
+    () => assertUnreachable('Should have failed due to bad with object'),
+    error => result7 = error.message);
+import('modules-skip-1.json', { with: { a: undefined }}).then(
+    () => assertUnreachable('Should have failed due to bad assertion value'),
+    error => result8 = error.message);
+import('modules-skip-1.json', { with: { a: 7 }}).then(
+    () => assertUnreachable('Should have failed due to bad assertion value'),
+    error => result9 = error.message);
+    import('modules-skip-1.json', { with: { a: { } }}).then(
+        () => assertUnreachable('Should have failed due to bad assertion value'),
+        error => result10 = error.message);
+
+%PerformMicrotaskCheckpoint();
+
+const argumentNotObjectError = 'The second argument to import() must be an object';
+const assertOptionNotObjectError = 'The \'assert\' option must be an object';
+const assertionValueNotStringError = 'Import assertion value must be a string';
+
+assertEquals(argumentNotObjectError, result1);
+assertEquals(argumentNotObjectError, result2);
+assertEquals(argumentNotObjectError, result3);
+assertEquals(assertOptionNotObjectError, result4);
+assertEquals(assertOptionNotObjectError, result5);
+assertEquals(assertOptionNotObjectError, result6);
+assertEquals(assertionValueNotStringError, result7);
+assertEquals(assertionValueNotStringError, result8);
+assertEquals(assertionValueNotStringError, result9);
+assertEquals(assertionValueNotStringError, result10);
diff --git a/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-8.mjs b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-8.mjs
new file mode 100644
index 00000000000000..74a4504e253d6a
--- /dev/null
+++ b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-8.mjs
@@ -0,0 +1,13 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax --harmony-import-attributes
+
+var life;
+import('modules-skip-1.mjs', undefined).then(
+    namespace => life = namespace.life());
+
+%PerformMicrotaskCheckpoint();
+
+assertEquals(42, life);
diff --git a/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-9.mjs b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-9.mjs
new file mode 100644
index 00000000000000..1b56c70df61682
--- /dev/null
+++ b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-9.mjs
@@ -0,0 +1,13 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax --harmony-import-attributes
+
+var life;
+import('modules-skip-1.mjs', { with: undefined }).then(
+    namespace => life = namespace.life());
+
+%PerformMicrotaskCheckpoint();
+
+assertEquals(42, life);
diff --git a/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-assertions-fallback-1.mjs b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-assertions-fallback-1.mjs
new file mode 100644
index 00000000000000..3faaf0dccea1c9
--- /dev/null
+++ b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-assertions-fallback-1.mjs
@@ -0,0 +1,15 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax --harmony-import-attributes --harmony-import-assertions
+
+var life;
+import('modules-skip-1.mjs', {
+    with: {},
+    get assert() { throw 'Should not read assert'; }
+}).then(namespace => life = namespace.life());
+
+%PerformMicrotaskCheckpoint();
+
+assertEquals(42, life);
diff --git a/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-assertions-fallback-2.mjs b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-assertions-fallback-2.mjs
new file mode 100644
index 00000000000000..4c83d2fbd716cc
--- /dev/null
+++ b/deps/v8/test/mjsunit/harmony/modules-import-attributes-dynamic-assertions-fallback-2.mjs
@@ -0,0 +1,15 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax --harmony-import-attributes --harmony-import-assertions
+
+var life;
+import('modules-skip-1.json', {
+    with: undefined,
+    assert: { type: 'json' }
+}).then(namespace => life = namespace.default.life);
+
+%PerformMicrotaskCheckpoint();
+
+assertEquals(42, life);
diff --git a/doc/api/esm.md b/doc/api/esm.md
index 9b629f2a2a997d..448a3c119513fd 100644
--- a/doc/api/esm.md
+++ b/doc/api/esm.md
@@ -7,6 +7,9 @@
 <!-- YAML
 added: v8.5.0
 changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/50140
+    description: Add experimental support for import attributes.
   - version: v18.19.0
     pr-url: https://github.com/nodejs/node/pull/44710
     description: Module customization hooks are executed off the main thread.
@@ -202,7 +205,7 @@ added: v12.10.0
 
 ```js
 import 'data:text/javascript,console.log("hello!");';
-import _ from 'data:application/json,"world!"' assert { type: 'json' };
+import _ from 'data:application/json,"world!"' with { type: 'json' };
 ```
 
 `data:` URLs only resolve [bare specifiers][Terminology] for builtin modules
@@ -243,7 +246,7 @@ added:
   - v17.1.0
   - v16.14.0
 changes:
-  - version: v18.19.0
+  - version: REPLACEME
     pr-url: https://github.com/nodejs/node/pull/50140
     description: Switch from Import Assertions to Import Attributes.
 -->
@@ -251,18 +254,17 @@ changes:
 > Stability: 1.1 - Active development
 
 > This feature was previously named "Import assertions", and using the `assert`
-> keyword instead of `with`. Because the version of V8 on this release line does
-> not support the `with` keyword, you need to keep using `assert` to support
-> this version of Node.js.
+> keyword instead of `with`. Any uses in code of the prior `assert` keyword
+> should be updated to use `with` instead.
 
 The [Import Attributes proposal][] adds an inline syntax for module import
 statements to pass on more information alongside the module specifier.
 
 ```js
-import fooData from './foo.json' assert { type: 'json' };
+import fooData from './foo.json' with { type: 'json' };
 
 const { default: barData } =
-  await import('./bar.json', { assert: { type: 'json' } });
+  await import('./bar.json', { with: { type: 'json' } });
 ```
 
 Node.js supports the following `type` values, for which the attribute is
@@ -555,10 +557,10 @@ separate cache.
 JSON files can be referenced by `import`:
 
 ```js
-import packageConfig from './package.json' assert { type: 'json' };
+import packageConfig from './package.json' with { type: 'json' };
 ```
 
-The `assert { type: 'json' }` syntax is mandatory; see [Import Attributes][].
+The `with { type: 'json' }` syntax is mandatory; see [Import Attributes][].
 
 The imported JSON only exposes a `default` export. There is no support for named
 exports. A cache entry is created in the CommonJS cache to avoid duplication.
diff --git a/doc/api/vm.md b/doc/api/vm.md
index f405d71ef299d4..cda624731666f3 100644
--- a/doc/api/vm.md
+++ b/doc/api/vm.md
@@ -101,7 +101,7 @@ changes:
     using it in a production environment.
     * `specifier` {string} specifier passed to `import()`
     * `script` {vm.Script}
-    * `importAttributes` {Object} The `"assert"` value passed to the
+    * `importAttributes` {Object} The `"with"` value passed to the
       [`optionsExpression`][] optional parameter, or an empty object if no value
       was provided.
     * Returns: {Module Namespace Object|vm.Module} Returning a `vm.Module` is
@@ -633,7 +633,7 @@ changes:
   * `extra` {Object}
     * `attributes` {Object} The data from the attribute:
       ```mjs
-      import foo from 'foo' assert { name: 'value' };
+      import foo from 'foo' with { name: 'value' };
       //                           ^^^^^^^^^^^^^^^^^ the attribute
       ```
       Per ECMA-262, hosts are expected to trigger an error if an
@@ -1025,7 +1025,7 @@ changes:
     considered stable.
     * `specifier` {string} specifier passed to `import()`
     * `function` {Function}
-    * `importAttributes` {Object} The `"assert"` value passed to the
+    * `importAttributes` {Object} The `"with"` value passed to the
       [`optionsExpression`][] optional parameter, or an empty object if no value
       was provided.
     * Returns: {Module Namespace Object|vm.Module} Returning a `vm.Module` is
@@ -1249,7 +1249,7 @@ changes:
     using it in a production environment.
     * `specifier` {string} specifier passed to `import()`
     * `script` {vm.Script}
-    * `importAttributes` {Object} The `"assert"` value passed to the
+    * `importAttributes` {Object} The `"with"` value passed to the
       [`optionsExpression`][] optional parameter, or an empty object if no value
       was provided.
     * Returns: {Module Namespace Object|vm.Module} Returning a `vm.Module` is
@@ -1348,7 +1348,7 @@ changes:
     using it in a production environment.
     * `specifier` {string} specifier passed to `import()`
     * `script` {vm.Script}
-    * `importAttributes` {Object} The `"assert"` value passed to the
+    * `importAttributes` {Object} The `"with"` value passed to the
       [`optionsExpression`][] optional parameter, or an empty object if no value
       was provided.
     * Returns: {Module Namespace Object|vm.Module} Returning a `vm.Module` is
@@ -1428,7 +1428,7 @@ changes:
     using it in a production environment.
     * `specifier` {string} specifier passed to `import()`
     * `script` {vm.Script}
-    * `importAttributes` {Object} The `"assert"` value passed to the
+    * `importAttributes` {Object} The `"with"` value passed to the
       [`optionsExpression`][] optional parameter, or an empty object if no value
       was provided.
     * Returns: {Module Namespace Object|vm.Module} Returning a `vm.Module` is
diff --git a/src/module_wrap.cc b/src/module_wrap.cc
index 21b9a702aebaf4..a11be73b7d4bdc 100644
--- a/src/module_wrap.cc
+++ b/src/module_wrap.cc
@@ -251,10 +251,14 @@ void ModuleWrap::New(const FunctionCallbackInfo<Value>& args) {
 }
 
 static Local<Object> createImportAttributesContainer(
-    Environment* env, Isolate* isolate, Local<FixedArray> raw_attributes) {
+    Environment* env,
+    Isolate* isolate,
+    Local<FixedArray> raw_attributes,
+    const int elements_per_attribute) {
+  CHECK_EQ(raw_attributes->Length() % elements_per_attribute, 0);
   Local<Object> attributes =
       Object::New(isolate, v8::Null(env->isolate()), nullptr, nullptr, 0);
-  for (int i = 0; i < raw_attributes->Length(); i += 3) {
+  for (int i = 0; i < raw_attributes->Length(); i += elements_per_attribute) {
     attributes
         ->Set(env->context(),
               raw_attributes->Get(env->context(), i).As<String>(),
@@ -300,7 +304,7 @@ void ModuleWrap::Link(const FunctionCallbackInfo<Value>& args) {
 
     Local<FixedArray> raw_attributes = module_request->GetImportAssertions();
     Local<Object> attributes =
-        createImportAttributesContainer(env, isolate, raw_attributes);
+        createImportAttributesContainer(env, isolate, raw_attributes, 3);
 
     Local<Value> argv[] = {
         specifier,
@@ -603,7 +607,7 @@ static MaybeLocal<Promise> ImportModuleDynamically(
   }
 
   Local<Object> attributes =
-      createImportAttributesContainer(env, isolate, import_attributes);
+      createImportAttributesContainer(env, isolate, import_attributes, 2);
 
   Local<Value> import_args[] = {
     object,
diff --git a/src/node.cc b/src/node.cc
index 0c75b5a08edd05..367d47325b7d5e 100644
--- a/src/node.cc
+++ b/src/node.cc
@@ -745,6 +745,13 @@ int ProcessGlobalArgs(std::vector<std::string>* args,
                 "--no-harmony-import-assertions") == v8_args.end()) {
     v8_args.emplace_back("--harmony-import-assertions");
   }
+  // TODO(aduh95): remove this when the harmony-import-attributes flag
+  // is removed in V8.
+  if (std::find(v8_args.begin(),
+                v8_args.end(),
+                "--no-harmony-import-attributes") == v8_args.end()) {
+    v8_args.emplace_back("--harmony-import-attributes");
+  }
 
   auto env_opts = per_process::cli_options->per_isolate->per_env;
   if (std::find(v8_args.begin(), v8_args.end(),
diff --git a/test/es-module/test-esm-assertionless-json-import.js b/test/es-module/test-esm-assertionless-json-import.js
index 23c71a1ba105d2..bd8acdae995a76 100644
--- a/test/es-module/test-esm-assertionless-json-import.js
+++ b/test/es-module/test-esm-assertionless-json-import.js
@@ -9,7 +9,7 @@ async function test() {
       import('../fixtures/experimental.json'),
       import(
         '../fixtures/experimental.json',
-        { assert: { type: 'json' } }
+        { with: { type: 'json' } }
       ),
     ]);
 
@@ -24,7 +24,7 @@ async function test() {
       import('../fixtures/experimental.json?test'),
       import(
         '../fixtures/experimental.json?test',
-        { assert: { type: 'json' } }
+        { with: { type: 'json' } }
       ),
     ]);
 
@@ -39,7 +39,7 @@ async function test() {
       import('../fixtures/experimental.json#test'),
       import(
         '../fixtures/experimental.json#test',
-        { assert: { type: 'json' } }
+        { with: { type: 'json' } }
       ),
     ]);
 
@@ -54,7 +54,7 @@ async function test() {
       import('../fixtures/experimental.json?test2#test'),
       import(
         '../fixtures/experimental.json?test2#test',
-        { assert: { type: 'json' } }
+        { with: { type: 'json' } }
       ),
     ]);
 
@@ -69,7 +69,7 @@ async function test() {
       import('data:application/json,{"ofLife":42}'),
       import(
         'data:application/json,{"ofLife":42}',
-        { assert: { type: 'json' } }
+        { with: { type: 'json' } }
       ),
     ]);
 
diff --git a/test/es-module/test-esm-data-urls.js b/test/es-module/test-esm-data-urls.js
index 5be45d0f7af3b6..a0add97b6f64ad 100644
--- a/test/es-module/test-esm-data-urls.js
+++ b/test/es-module/test-esm-data-urls.js
@@ -60,21 +60,21 @@ function createBase64URL(mime, body) {
   }
   {
     const ns = await import('data:application/json;foo="test,"this"',
-      { assert: { type: 'json' } });
+      { with: { type: 'json' } });
     assert.deepStrictEqual(Object.keys(ns), ['default']);
     assert.strictEqual(ns.default, 'this');
   }
   {
     const ns = await import(`data:application/json;foo=${
       encodeURIComponent('test,')
-    },0`, { assert: { type: 'json' } });
+    },0`, { with: { type: 'json' } });
     assert.deepStrictEqual(Object.keys(ns), ['default']);
     assert.strictEqual(ns.default, 0);
   }
   {
     await assert.rejects(async () =>
       import('data:application/json;foo="test,",0',
-        { assert: { type: 'json' } }), {
+        { with: { type: 'json' } }), {
       name: 'SyntaxError',
       message: /Unexpected end of JSON input/
     });
@@ -82,14 +82,14 @@ function createBase64URL(mime, body) {
   {
     const body = '{"x": 1}';
     const plainESMURL = createURL('application/json', body);
-    const ns = await import(plainESMURL, { assert: { type: 'json' } });
+    const ns = await import(plainESMURL, { with: { type: 'json' } });
     assert.deepStrictEqual(Object.keys(ns), ['default']);
     assert.strictEqual(ns.default.x, 1);
   }
   {
     const body = '{"default": 2}';
     const plainESMURL = createURL('application/json', body);
-    const ns = await import(plainESMURL, { assert: { type: 'json' } });
+    const ns = await import(plainESMURL, { with: { type: 'json' } });
     assert.deepStrictEqual(Object.keys(ns), ['default']);
     assert.strictEqual(ns.default.default, 2);
   }
diff --git a/test/es-module/test-esm-dynamic-import-attribute.js b/test/es-module/test-esm-dynamic-import-attribute.js
index 71ef9cd1d1d30b..4558cd27ca4237 100644
--- a/test/es-module/test-esm-dynamic-import-attribute.js
+++ b/test/es-module/test-esm-dynamic-import-attribute.js
@@ -5,7 +5,7 @@ const { strictEqual } = require('assert');
 async function test() {
   {
     const results = await Promise.allSettled([
-      import('../fixtures/empty.js', { assert: { type: 'json' } }),
+      import('../fixtures/empty.js', { with: { type: 'json' } }),
       import('../fixtures/empty.js'),
     ]);
 
@@ -16,7 +16,7 @@ async function test() {
   {
     const results = await Promise.allSettled([
       import('../fixtures/empty.js'),
-      import('../fixtures/empty.js', { assert: { type: 'json' } }),
+      import('../fixtures/empty.js', { with: { type: 'json' } }),
     ]);
 
     strictEqual(results[0].status, 'fulfilled');
@@ -25,7 +25,7 @@ async function test() {
 
   {
     const results = await Promise.allSettled([
-      import('../fixtures/empty.json', { assert: { type: 'json' } }),
+      import('../fixtures/empty.json', { with: { type: 'json' } }),
       import('../fixtures/empty.json'),
     ]);
 
@@ -36,7 +36,7 @@ async function test() {
   {
     const results = await Promise.allSettled([
       import('../fixtures/empty.json'),
-      import('../fixtures/empty.json', { assert: { type: 'json' } }),
+      import('../fixtures/empty.json', { with: { type: 'json' } }),
     ]);
 
     strictEqual(results[0].status, 'rejected');
diff --git a/test/es-module/test-esm-dynamic-import-attribute.mjs b/test/es-module/test-esm-dynamic-import-attribute.mjs
index 4010259b743cbd..b3d2cb20c36e34 100644
--- a/test/es-module/test-esm-dynamic-import-attribute.mjs
+++ b/test/es-module/test-esm-dynamic-import-attribute.mjs
@@ -3,7 +3,7 @@ import { strictEqual } from 'assert';
 
 {
   const results = await Promise.allSettled([
-    import('../fixtures/empty.js', { assert: { type: 'json' } }),
+    import('../fixtures/empty.js', { with: { type: 'json' } }),
     import('../fixtures/empty.js'),
   ]);
 
@@ -14,7 +14,7 @@ import { strictEqual } from 'assert';
 {
   const results = await Promise.allSettled([
     import('../fixtures/empty.js'),
-    import('../fixtures/empty.js', { assert: { type: 'json' } }),
+    import('../fixtures/empty.js', { with: { type: 'json' } }),
   ]);
 
   strictEqual(results[0].status, 'fulfilled');
@@ -23,7 +23,7 @@ import { strictEqual } from 'assert';
 
 {
   const results = await Promise.allSettled([
-    import('../fixtures/empty.json', { assert: { type: 'json' } }),
+    import('../fixtures/empty.json', { with: { type: 'json' } }),
     import('../fixtures/empty.json'),
   ]);
 
@@ -34,7 +34,7 @@ import { strictEqual } from 'assert';
 {
   const results = await Promise.allSettled([
     import('../fixtures/empty.json'),
-    import('../fixtures/empty.json', { assert: { type: 'json' } }),
+    import('../fixtures/empty.json', { with: { type: 'json' } }),
   ]);
 
   strictEqual(results[0].status, 'rejected');
diff --git a/test/es-module/test-esm-import-attributes-1.mjs b/test/es-module/test-esm-import-attributes-1.mjs
index 72b3426bdbb601..c699a27bb51a75 100644
--- a/test/es-module/test-esm-import-attributes-1.mjs
+++ b/test/es-module/test-esm-import-attributes-1.mjs
@@ -1,6 +1,6 @@
 import '../common/index.mjs';
 import { strictEqual } from 'assert';
 
-import secret from '../fixtures/experimental.json' assert { type: 'json' };
+import secret from '../fixtures/experimental.json' with { type: 'json' };
 
 strictEqual(secret.ofLife, 42);
diff --git a/test/es-module/test-esm-import-attributes-2.mjs b/test/es-module/test-esm-import-attributes-2.mjs
index 1b4669ac276474..85d6020019af05 100644
--- a/test/es-module/test-esm-import-attributes-2.mjs
+++ b/test/es-module/test-esm-import-attributes-2.mjs
@@ -1,9 +1,9 @@
 import '../common/index.mjs';
 import { strictEqual } from 'assert';
 
-import secret0 from '../fixtures/experimental.json' assert { type: 'json' };
+import secret0 from '../fixtures/experimental.json' with { type: 'json' };
 const secret1 = await import('../fixtures/experimental.json', {
-  assert: { type: 'json' },
+  with: { type: 'json' },
 });
 
 strictEqual(secret0.ofLife, 42);
diff --git a/test/es-module/test-esm-import-attributes-3.mjs b/test/es-module/test-esm-import-attributes-3.mjs
index b9de9232cfff4d..8950ca5c595e12 100644
--- a/test/es-module/test-esm-import-attributes-3.mjs
+++ b/test/es-module/test-esm-import-attributes-3.mjs
@@ -1,9 +1,9 @@
 import '../common/index.mjs';
 import { strictEqual } from 'assert';
 
-import secret0 from '../fixtures/experimental.json' assert { type: 'json' };
+import secret0 from '../fixtures/experimental.json' with { type: 'json' };
 const secret1 = await import('../fixtures/experimental.json',
-  { assert: { type: 'json' } });
+  { with: { type: 'json' } });
 
 strictEqual(secret0.ofLife, 42);
 strictEqual(secret1.default.ofLife, 42);
diff --git a/test/es-module/test-esm-import-attributes-errors.js b/test/es-module/test-esm-import-attributes-errors.js
index f6e57f19b6b432..976d4a3f67f778 100644
--- a/test/es-module/test-esm-import-attributes-errors.js
+++ b/test/es-module/test-esm-import-attributes-errors.js
@@ -7,27 +7,32 @@ const jsonModuleDataUrl = 'data:application/json,""';
 
 async function test() {
   await rejects(
-    import('data:text/css,', { assert: { type: 'css' } }),
+    import('data:text/css,', { with: { type: 'css' } }),
     { code: 'ERR_UNKNOWN_MODULE_FORMAT' }
   );
 
   await rejects(
-    import('data:text/css,', { assert: { unsupportedAttribute: 'value' } }),
+    import('data:text/css,', { with: { unsupportedAttribute: 'value' } }),
     { code: 'ERR_IMPORT_ATTRIBUTE_UNSUPPORTED' }
   );
 
   await rejects(
-    import(`data:text/javascript,import${JSON.stringify(jsModuleDataUrl)}assert{type:"json"}`),
+    import(`data:text/javascript,import${JSON.stringify(jsModuleDataUrl)}with{type:"json"}`),
     { code: 'ERR_IMPORT_ASSERTION_TYPE_FAILED' }
   );
 
   await rejects(
-    import(jsModuleDataUrl, { assert: { type: 'json' } }),
+    import(jsModuleDataUrl, { with: { type: 'json' } }),
     { code: 'ERR_IMPORT_ASSERTION_TYPE_FAILED' }
   );
 
   await rejects(
-    import(jsModuleDataUrl, { assert: { type: 'unsupported' } }),
+    import(jsModuleDataUrl, { with: { type: 'json', other: 'unsupported' } }),
+    { code: 'ERR_IMPORT_ASSERTION_TYPE_FAILED' }
+  );
+
+  await rejects(
+    import(jsModuleDataUrl, { with: { type: 'unsupported' } }),
     { code: 'ERR_IMPORT_ASSERTION_TYPE_UNSUPPORTED' }
   );
 
@@ -37,17 +42,17 @@ async function test() {
   );
 
   await rejects(
-    import(jsonModuleDataUrl, { assert: {} }),
+    import(jsonModuleDataUrl, { with: {} }),
     { code: 'ERR_IMPORT_ASSERTION_TYPE_MISSING' }
   );
 
   await rejects(
-    import(jsonModuleDataUrl, { assert: { foo: 'bar' } }),
+    import(jsonModuleDataUrl, { with: { foo: 'bar' } }),
     { code: 'ERR_IMPORT_ASSERTION_TYPE_MISSING' }
   );
 
   await rejects(
-    import(jsonModuleDataUrl, { assert: { type: 'unsupported' } }),
+    import(jsonModuleDataUrl, { with: { type: 'unsupported' } }),
     { code: 'ERR_IMPORT_ASSERTION_TYPE_UNSUPPORTED' }
   );
 }
diff --git a/test/es-module/test-esm-import-attributes-errors.mjs b/test/es-module/test-esm-import-attributes-errors.mjs
index 6621585be412e0..072b94b1b0fc55 100644
--- a/test/es-module/test-esm-import-attributes-errors.mjs
+++ b/test/es-module/test-esm-import-attributes-errors.mjs
@@ -7,22 +7,27 @@ const jsonModuleDataUrl = 'data:application/json,""';
 await rejects(
   // This rejects because of the unsupported MIME type, not because of the
   // unsupported assertion.
-  import('data:text/css,', { assert: { type: 'css' } }),
+  import('data:text/css,', { with: { type: 'css' } }),
   { code: 'ERR_UNKNOWN_MODULE_FORMAT' }
 );
 
 await rejects(
-  import(`data:text/javascript,import${JSON.stringify(jsModuleDataUrl)}assert{type:"json"}`),
+  import(`data:text/javascript,import${JSON.stringify(jsModuleDataUrl)}with{type:"json"}`),
   { code: 'ERR_IMPORT_ASSERTION_TYPE_FAILED' }
 );
 
 await rejects(
-  import(jsModuleDataUrl, { assert: { type: 'json' } }),
+  import(jsModuleDataUrl, { with: { type: 'json' } }),
   { code: 'ERR_IMPORT_ASSERTION_TYPE_FAILED' }
 );
 
 await rejects(
-  import(import.meta.url, { assert: { type: 'unsupported' } }),
+  import(jsModuleDataUrl, { with: { type: 'json', other: 'unsupported' } }),
+  { code: 'ERR_IMPORT_ASSERTION_TYPE_FAILED' }
+);
+
+await rejects(
+  import(import.meta.url, { with: { type: 'unsupported' } }),
   { code: 'ERR_IMPORT_ASSERTION_TYPE_UNSUPPORTED' }
 );
 
@@ -32,16 +37,16 @@ await rejects(
 );
 
 await rejects(
-  import(jsonModuleDataUrl, { assert: {} }),
+  import(jsonModuleDataUrl, { with: {} }),
   { code: 'ERR_IMPORT_ASSERTION_TYPE_MISSING' }
 );
 
 await rejects(
-  import(jsonModuleDataUrl, { assert: { foo: 'bar' } }),
+  import(jsonModuleDataUrl, { with: { foo: 'bar' } }),
   { code: 'ERR_IMPORT_ASSERTION_TYPE_MISSING' }
 );
 
 await rejects(
-  import(jsonModuleDataUrl, { assert: { type: 'unsupported' } }),
+  import(jsonModuleDataUrl, { with: { type: 'unsupported' } }),
   { code: 'ERR_IMPORT_ASSERTION_TYPE_UNSUPPORTED' }
 );
diff --git a/test/es-module/test-esm-json-cache.mjs b/test/es-module/test-esm-json-cache.mjs
index b766519d663f9a..f8d24fd394a4a2 100644
--- a/test/es-module/test-esm-json-cache.mjs
+++ b/test/es-module/test-esm-json-cache.mjs
@@ -6,7 +6,7 @@ import { createRequire } from 'module';
 
 import mod from '../fixtures/es-modules/json-cache/mod.cjs';
 import another from '../fixtures/es-modules/json-cache/another.cjs';
-import test from '../fixtures/es-modules/json-cache/test.json' assert
+import test from '../fixtures/es-modules/json-cache/test.json' with
   { type: 'json' };
 
 const require = createRequire(import.meta.url);
diff --git a/test/es-module/test-esm-json.mjs b/test/es-module/test-esm-json.mjs
index e5a0ab9f74e2cf..422a8f717594ab 100644
--- a/test/es-module/test-esm-json.mjs
+++ b/test/es-module/test-esm-json.mjs
@@ -7,7 +7,7 @@ import { describe, it, test } from 'node:test';
 import { mkdir, rm, writeFile } from 'node:fs/promises';
 import * as tmpdir from '../common/tmpdir.js';
 
-import secret from '../fixtures/experimental.json' assert { type: 'json' };
+import secret from '../fixtures/experimental.json' with { type: 'json' };
 
 describe('ESM: importing JSON', () => {
   it('should load JSON', () => {
@@ -34,19 +34,19 @@ describe('ESM: importing JSON', () => {
         const url = new URL('./foo.json', root);
         await writeFile(url, JSON.stringify({ id: i++ }));
         const absoluteURL = await import(`${url}`, {
-          assert: { type: 'json' },
+          with: { type: 'json' },
         });
         await writeFile(url, JSON.stringify({ id: i++ }));
         const queryString = await import(`${url}?a=2`, {
-          assert: { type: 'json' },
+          with: { type: 'json' },
         });
         await writeFile(url, JSON.stringify({ id: i++ }));
         const hash = await import(`${url}#a=2`, {
-          assert: { type: 'json' },
+          with: { type: 'json' },
         });
         await writeFile(url, JSON.stringify({ id: i++ }));
         const queryStringAndHash = await import(`${url}?a=2#a=2`, {
-          assert: { type: 'json' },
+          with: { type: 'json' },
         });
 
         assert.notDeepStrictEqual(absoluteURL, queryString);
diff --git a/test/es-module/test-esm-virtual-json.mjs b/test/es-module/test-esm-virtual-json.mjs
index 8876eea013ced8..a42b037fc1f200 100644
--- a/test/es-module/test-esm-virtual-json.mjs
+++ b/test/es-module/test-esm-virtual-json.mjs
@@ -25,6 +25,6 @@ function load(url, context, next) {
 register(`data:text/javascript,export ${encodeURIComponent(resolve)};export ${encodeURIComponent(load)}`);
 
 assert.notDeepStrictEqual(
-  await import(fixtures.fileURL('empty.json'), { assert: { type: 'json' } }),
-  await import(fixtures.fileURL('empty.json'), { assert: { type: 'json' } }),
+  await import(fixtures.fileURL('empty.json'), { with: { type: 'json' } }),
+  await import(fixtures.fileURL('empty.json'), { with: { type: 'json' } }),
 );
diff --git a/test/fixtures/es-modules/import-json-named-export.mjs b/test/fixtures/es-modules/import-json-named-export.mjs
index 01798c59ac587d..be1a4116eb5ffa 100644
--- a/test/fixtures/es-modules/import-json-named-export.mjs
+++ b/test/fixtures/es-modules/import-json-named-export.mjs
@@ -1 +1 @@
-import { ofLife } from '../experimental.json' assert { type: 'json' };
+import { ofLife } from '../experimental.json' with { type: 'json' };
diff --git a/test/fixtures/es-modules/json-modules.mjs b/test/fixtures/es-modules/json-modules.mjs
index 607c09e51cda2b..c1eae2b689a696 100644
--- a/test/fixtures/es-modules/json-modules.mjs
+++ b/test/fixtures/es-modules/json-modules.mjs
@@ -1 +1 @@
-import secret from '../experimental.json' assert { type: 'json' };
+import secret from '../experimental.json' with { type: 'json' };
diff --git a/test/parallel/test-vm-module-dynamic-import.js b/test/parallel/test-vm-module-dynamic-import.js
index 5bca08b8c9c3bb..b74d3b28d7a547 100644
--- a/test/parallel/test-vm-module-dynamic-import.js
+++ b/test/parallel/test-vm-module-dynamic-import.js
@@ -58,7 +58,7 @@ async function test() {
   }
 
   {
-    const s = new Script('import("foo", { assert: { key: "value" } })', {
+    const s = new Script('import("foo", { with: { key: "value" } })', {
       importModuleDynamically: common.mustCall((specifier, wrap, attributes) => {
         assert.strictEqual(specifier, 'foo');
         assert.strictEqual(wrap, s);