diff --git a/shell/platform/windows/text_input_plugin.cc b/shell/platform/windows/text_input_plugin.cc
index ebfe004292644..4d3cac7add4d2 100644
--- a/shell/platform/windows/text_input_plugin.cc
+++ b/shell/platform/windows/text_input_plugin.cc
@@ -16,6 +16,9 @@ static constexpr char kClearClientMethod[] = "TextInput.clearClient";
 static constexpr char kSetClientMethod[] = "TextInput.setClient";
 static constexpr char kShowMethod[] = "TextInput.show";
 static constexpr char kHideMethod[] = "TextInput.hide";
+static constexpr char kSetMarkedTextRect[] = "TextInput.setMarkedTextRect";
+static constexpr char kSetEditableSizeAndTransform[] =
+    "TextInput.setEditableSizeAndTransform";
 
 static constexpr char kMultilineInputType[] = "TextInputType.multiline";
 
@@ -34,6 +37,11 @@ static constexpr char kSelectionBaseKey[] = "selectionBase";
 static constexpr char kSelectionExtentKey[] = "selectionExtent";
 static constexpr char kSelectionIsDirectionalKey[] = "selectionIsDirectional";
 static constexpr char kTextKey[] = "text";
+static constexpr char kXKey[] = "x";
+static constexpr char kYKey[] = "y";
+static constexpr char kWidthKey[] = "width";
+static constexpr char kHeightKey[] = "height";
+static constexpr char kTransformKey[] = "transform";
 
 static constexpr char kChannelName[] = "flutter/textinput";
 
@@ -171,6 +179,49 @@ void TextInputPlugin::HandleMethodCall(
     }
     active_model_->SetText(text->value.GetString());
     active_model_->SetSelection(TextRange(base, extent));
+  } else if (method.compare(kSetMarkedTextRect) == 0) {
+    if (!method_call.arguments() || method_call.arguments()->IsNull()) {
+      result->Error(kBadArgumentError, "Method invoked without args");
+      return;
+    }
+    const rapidjson::Document& args = *method_call.arguments();
+    auto x = args.FindMember(kXKey);
+    auto y = args.FindMember(kYKey);
+    auto width = args.FindMember(kWidthKey);
+    auto height = args.FindMember(kHeightKey);
+    if (x == args.MemberEnd() || x->value.IsNull() ||
+        y == args.MemberEnd() || y->value.IsNull() ||
+        width == args.MemberEnd() || width->value.IsNull() ||
+        height == args.MemberEnd() || height->value.IsNull()) {
+      result->Error(kInternalConsistencyError, "Composing rect values invalid.");
+      return;
+    }
+    compose_rect_.x = x->value.GetDouble();
+    compose_rect_.y = y->value.GetDouble();
+    compose_rect_.width = width->value.GetDouble();
+    compose_rect_.height = height->value.GetDouble();
+  } else if (method.compare(kSetEditableSizeAndTransform) == 0) {
+    if (!method_call.arguments() || method_call.arguments()->IsNull()) {
+      result->Error(kBadArgumentError, "Method invoked without args");
+      return;
+    }
+    const rapidjson::Document& args = *method_call.arguments();
+    auto transform = args.FindMember(kTransformKey);
+    if (transform == args.MemberEnd() || transform->value.IsNull() ||
+        !transform->value.IsArray() || transform->value.Size() != 16) {
+      result->Error(kInternalConsistencyError, "EditableText transform invalid.");
+      return;
+    }
+    size_t i = 0;
+    for (auto& entry : transform->value.GetArray()) {
+      if (entry.IsNull()) {
+        result->Error(kInternalConsistencyError,
+                      "EditableText transform contains null value.");
+        return;
+      }
+      editabletext_transform_[i / 4][i % 4] = entry.GetDouble();
+      ++i;
+    }
   } else {
     result->NotImplemented();
     return;
diff --git a/shell/platform/windows/text_input_plugin.h b/shell/platform/windows/text_input_plugin.h
index d74b2516afcf3..837549996d3ff 100644
--- a/shell/platform/windows/text_input_plugin.h
+++ b/shell/platform/windows/text_input_plugin.h
@@ -19,6 +19,21 @@ namespace flutter {
 
 class FlutterWindowsView;
 
+// A rectangle with a position and extent.
+//
+// Used to store the current composing rectangle when using multi-step (IME)
+// text input.
+struct Rect {
+  Rect() = default;
+  Rect(const Rect& rect) = default;
+  Rect& operator=(const Rect& other) = default;
+
+  double x;
+  double y;
+  double width;
+  double height;
+};
+
 // Implements a text input plugin.
 //
 // Specifically handles window events within windows.
@@ -50,6 +65,10 @@ class TextInputPlugin : public KeyboardHookHandler {
       const flutter::MethodCall<rapidjson::Document>& method_call,
       std::unique_ptr<flutter::MethodResult<rapidjson::Document>> result);
 
+  void SetMarkedTextRect(
+      const flutter::MethodCall<rapidjson::Document>& method_call,
+      std::unique_ptr<flutter::MethodResult<rapidjson::Document>> result);
+
   // The MethodChannel used for communication with the Flutter engine.
   std::unique_ptr<flutter::MethodChannel<rapidjson::Document>> channel_;
 
@@ -66,6 +85,16 @@ class TextInputPlugin : public KeyboardHookHandler {
   // An action requested by the user on the input client. See available options:
   // https://api.flutter.dev/flutter/services/TextInputAction-class.html
   std::string input_action_;
+
+  // The smallest rect, in local coordinates, of the text in the composing
+  // range, or of the caret in the case where there is no current composing
+  // range. This value is updated via `TextInput.setMarkedTextRect` messages
+  // over the text input channel.
+  Rect compose_rect_;
+
+  // A 4x4 matrix that maps from `EditableText` local coordinates to the
+  // coordinate system of `PipelineOwner.rootNode`.
+  double editabletext_transform_[4][4];
 };
 
 }  // namespace flutter