diff --git a/eng/testing/tests.targets b/eng/testing/tests.targets
index 9336d5bdc24913..ee053db9bf4826 100644
--- a/eng/testing/tests.targets
+++ b/eng/testing/tests.targets
@@ -1,13 +1,16 @@
 <Project>
+  <!-- Define a shared predicate for platforms that support runtime async. -->
+  <PropertyGroup Condition="'$(RuntimeAsyncSupported)' == ''">
+    <RuntimeAsyncSupported Condition="'$(TargetOS)' != 'browser'
+      and '$(TargetOS)' != 'wasi'
+      and '$(TargetOS)' != 'android'
+      and '$(TargetsAppleMobile)' != 'true'
+      and '$(RuntimeFlavor)' != 'Mono'">true</RuntimeAsyncSupported>
+  </PropertyGroup>
+
   <!-- Enable runtime async for all .NET 11+ test projects. -->
   <PropertyGroup Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net11.0'))
-    and '$(TestNativeAot)' != 'true'
-    and ('$(TestReadyToRun)' != 'true' or '$(UseRuntimeAsync)' == 'true')
-    and '$(UseNativeAOTRuntime)' != 'true'
-    and '$(TargetOS)' != 'wasi'
-    and '$(TargetOS)' != 'android'
-    and '$(TargetsAppleMobile)' != 'true'
-    and '$(RuntimeFlavor)' != 'Mono'
+    and '$(RuntimeAsyncSupported)' == 'true'
     and '$(UseRuntimeAsync)' != 'false'">
     <EnablePreviewFeatures>true</EnablePreviewFeatures>
     <Features>$(Features);runtime-async=on</Features>
diff --git a/src/coreclr/inc/clrconfigvalues.h b/src/coreclr/inc/clrconfigvalues.h
index fd64be3df1b59f..78d11c697a1e88 100644
--- a/src/coreclr/inc/clrconfigvalues.h
+++ b/src/coreclr/inc/clrconfigvalues.h
@@ -715,9 +715,6 @@ RETAIL_CONFIG_DWORD_INFO(EXTERNAL_EnableRiscV64Zbb,             W("EnableRiscV64
 RETAIL_CONFIG_DWORD_INFO(EXTERNAL_EnableRiscV64Zbs,             W("EnableRiscV64Zbs"),          1, "Allows RiscV64 Zbs hardware intrinsics to be disabled")
 #endif
 
-// Runtime-async
-RETAIL_CONFIG_DWORD_INFO(UNSUPPORTED_RuntimeAsync, W("RuntimeAsync"), 1, "Enables runtime async method support")
-
 ///
 /// Uncategorized
 ///
diff --git a/src/coreclr/vm/eeconfig.cpp b/src/coreclr/vm/eeconfig.cpp
index 776febb4045381..97cc3a04c58df2 100644
--- a/src/coreclr/vm/eeconfig.cpp
+++ b/src/coreclr/vm/eeconfig.cpp
@@ -233,8 +233,6 @@ HRESULT EEConfig::Init()
     fGDBJitEmitDebugFrame = false;
 #endif
 
-    runtimeAsync = false;
-
     return S_OK;
 }
 
@@ -848,8 +846,6 @@ HRESULT EEConfig::sync()
     fUseCachedInterfaceDispatch = CLRConfig::GetConfigValue(CLRConfig::INTERNAL_UseCachedInterfaceDispatch) != 0;
 #endif // defined(FEATURE_CACHED_INTERFACE_DISPATCH) && defined(FEATURE_VIRTUAL_STUB_DISPATCH)
 
-    runtimeAsync = CLRConfig::GetConfigValue(CLRConfig::UNSUPPORTED_RuntimeAsync) != 0;
-
     return hr;
 }
 
diff --git a/src/coreclr/vm/eeconfig.h b/src/coreclr/vm/eeconfig.h
index fecb76eb69fb41..d57ea26c4bc1d5 100644
--- a/src/coreclr/vm/eeconfig.h
+++ b/src/coreclr/vm/eeconfig.h
@@ -449,8 +449,6 @@ class EEConfig
 
 #endif
 
-    bool    RuntimeAsync()                 const { LIMITED_METHOD_CONTRACT; return runtimeAsync; }
-
 #ifdef FEATURE_INTERPRETER
     bool    EnableInterpreter()            const { LIMITED_METHOD_CONTRACT; return enableInterpreter; }
 #endif
@@ -654,8 +652,6 @@ class EEConfig
     bool fUseCachedInterfaceDispatch;
 #endif // defined(FEATURE_CACHED_INTERFACE_DISPATCH) && defined(FEATURE_VIRTUAL_STUB_DISPATCH)
 
-    bool runtimeAsync; // True if the runtime supports async methods
-
 public:
 
     enum BitForMask {
diff --git a/src/coreclr/vm/method.cpp b/src/coreclr/vm/method.cpp
index 32d9a717280647..b11a65865c1bda 100644
--- a/src/coreclr/vm/method.cpp
+++ b/src/coreclr/vm/method.cpp
@@ -2392,13 +2392,6 @@ bool IsTypeDefOrRefImplementedInSystemModule(Module* pModule, mdToken tk)
 
 MethodReturnKind ClassifyMethodReturnKind(SigPointer sig, Module* pModule, ULONG* offsetOfAsyncDetails, bool *isValueTask)
 {
-    // Without runtime async, every declared method is classified as a NormalMethod.
-    // Thus code that handles runtime async scenarios becomes unreachable.
-    if (!g_pConfig->RuntimeAsync())
-    {
-        return MethodReturnKind::NormalMethod;
-    }
-
     PCCOR_SIGNATURE initialSig = sig.GetPtr();
     uint32_t data;
     IfFailThrow(sig.GetCallingConvInfo(&data));
diff --git a/src/libraries/Directory.Build.targets b/src/libraries/Directory.Build.targets
index 947dbfc3e71a66..87342ee832c6f6 100644
--- a/src/libraries/Directory.Build.targets
+++ b/src/libraries/Directory.Build.targets
@@ -127,8 +127,21 @@
                                                 '$(IsGeneratorProject)' != 'true'">true</SkipTargetingPackShimReferences>
   </PropertyGroup>
 
-  <!-- Enable runtime async for source projects when UseRuntimeAsync is set. -->
-  <PropertyGroup Condition="'$(UseRuntimeAsync)' == 'true' and '$(IsSourceProject)' == 'true'">
+  <!-- Define a shared predicate for platforms that support runtime async. -->
+  <PropertyGroup Condition="'$(RuntimeAsyncSupported)' == ''">
+    <RuntimeAsyncSupported Condition="'$(TargetOS)' != 'browser'
+      and '$(TargetOS)' != 'wasi'
+      and '$(TargetOS)' != 'android'
+      and '$(TargetsAppleMobile)' != 'true'
+      and '$(RuntimeFlavor)' != 'Mono'">true</RuntimeAsyncSupported>
+  </PropertyGroup>
+
+  <!-- Enable runtime async for netcoreapp source projects, excluding unsupported platforms and OOB packages. -->
+  <PropertyGroup Condition="'$(IsNETCoreAppSrc)' == 'true'
+    and '$(IsPackable)' != 'true'
+    and $([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net11.0'))
+    and '$(UseRuntimeAsync)' != 'false'
+    and '$(RuntimeAsyncSupported)' == 'true'">
     <EnablePreviewFeatures>true</EnablePreviewFeatures>
     <Features>$(Features);runtime-async=on</Features>
   </PropertyGroup>
diff --git a/src/tests/Interop/COM/RuntimeAsync/RuntimeAsync.csproj b/src/tests/Interop/COM/RuntimeAsync/RuntimeAsync.csproj
index 4a015bc375e61e..c3dcb6a823d350 100644
--- a/src/tests/Interop/COM/RuntimeAsync/RuntimeAsync.csproj
+++ b/src/tests/Interop/COM/RuntimeAsync/RuntimeAsync.csproj
@@ -1,7 +1,5 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <!-- RequiresProcessIsolation required for CLRTestEnvironmentVariable -->
-    <RequiresProcessIsolation>true</RequiresProcessIsolation>
     <Features>$(Features);runtime-async=on</Features>
   </PropertyGroup>
   <ItemGroup>
@@ -13,7 +11,4 @@
     <ProjectReference Include="$(TestLibraryProjectPath)" />
     <CMakeProjectReference Include="CMakeLists.txt" />
   </ItemGroup>
-  <ItemGroup>
-    <CLRTestEnvironmentVariable Include="DOTNET_RuntimeAsync" Value="1" />
-  </ItemGroup>
 </Project>