diff --git a/.github/actions/maestro-android/action.yml b/.github/actions/maestro-android/action.yml
index c45adeea6004d3..bf514a2d51576c 100644
--- a/.github/actions/maestro-android/action.yml
+++ b/.github/actions/maestro-android/action.yml
@@ -22,10 +22,6 @@ inputs:
     required: false
     default: "."
     description: The directory from which metro should be started
-  architecture:
-    required: false
-    default: "NewArch"
-    description: The react native architecture to test
 
 runs:
   using: composite
@@ -76,7 +72,7 @@ runs:
       uses: actions/upload-artifact@v4.3.4
       if: always()
       with:
-        name: e2e_android_${{ steps.normalize-app-id.outputs.app-id }}_report_${{ inputs.flavor }}_${{ inputs.architecture }}
+        name: e2e_android_${{ steps.normalize-app-id.outputs.app-id }}_report_${{ inputs.flavor }}_NewArch
         path: |
           report.xml
           screen.mp4
@@ -84,5 +80,5 @@ runs:
       if: steps.run-tests.outcome == 'failure'
       uses: actions/upload-artifact@v4.3.4
       with:
-        name: maestro-logs-android-${{ steps.normalize-app-id.outputs.app-id }}-${{ inputs.flavor }}-${{ inputs.architecture }}
+        name: maestro-logs-android-${{ steps.normalize-app-id.outputs.app-id }}-${{ inputs.flavor }}-NewArch
         path: /tmp/MaestroLogs
diff --git a/.github/actions/maestro-ios/action.yml b/.github/actions/maestro-ios/action.yml
index ce595dcb158a2c..5ba4f8dc2aaa66 100644
--- a/.github/actions/maestro-ios/action.yml
+++ b/.github/actions/maestro-ios/action.yml
@@ -18,10 +18,6 @@ inputs:
     required: false
     default: "."
     description: The directory from which metro should be started
-  architecture:
-    required: false
-    default: "NewArch"
-    description: The react native architecture to test
 
 runs:
   using: composite
@@ -70,7 +66,7 @@ runs:
       if: always()
       uses: actions/upload-artifact@v4.3.4
       with:
-        name: e2e_ios_${{ inputs.app-id }}_report_${{ inputs.flavor }}_${{ inputs.architecture }}
+        name: e2e_ios_${{ inputs.app-id }}_report_${{ inputs.flavor }}_NewArch
         path: |
           video_record_1.mov
           video_record_2.mov
@@ -82,5 +78,5 @@ runs:
       if: failure() && steps.run-tests.outcome == 'failure'
       uses: actions/upload-artifact@v4.3.4
       with:
-        name: maestro-logs-${{ inputs.app-id }}-${{ inputs.flavor }}-${{ inputs.architecture }}
+        name: maestro-logs-${{ inputs.app-id }}-${{ inputs.flavor }}-NewArch
         path: /tmp/MaestroLogs
diff --git a/.github/actions/setup-xcode-build-cache/action.yml b/.github/actions/setup-xcode-build-cache/action.yml
index 2f8932e6db428e..5d2187b06942b2 100644
--- a/.github/actions/setup-xcode-build-cache/action.yml
+++ b/.github/actions/setup-xcode-build-cache/action.yml
@@ -7,9 +7,6 @@ inputs:
   flavor:
     description: The flavor that is going to be built
     default: Debug
-  architecture:
-    description: The architecture that is going to be built
-    default: NewArch
   use-frameworks:
     description: Whether we are bulding with DynamicFrameworks or StaticLibraries
     default: StaticLibraries
@@ -27,9 +24,9 @@ runs:
       uses: actions/cache@v4
       with:
         path: packages/rn-tester/Podfile.lock
-        key: v13-podfilelock-${{ github.job }}-${{ inputs.architecture }}-${{ inputs.flavor }}-${{ inputs.use-frameworks }}-${{ inputs.ruby-version }}-${{ hashfiles('packages/rn-tester/Podfile') }}-${{ inputs.hermes-version }}
+        key: v13-podfilelock-${{ github.job }}-NewArch-${{ inputs.flavor }}-${{ inputs.use-frameworks }}-${{ inputs.ruby-version }}-${{ hashfiles('packages/rn-tester/Podfile') }}-${{ inputs.hermes-version }}
     - name: Cache cocoapods
       uses: actions/cache@v4
       with:
         path: packages/rn-tester/Pods
-        key: v15-cocoapods-${{ github.job }}-${{ inputs.architecture }}-${{ inputs.flavor }}-${{ inputs.use-frameworks }}-${{ inputs.ruby-version }}-${{ hashfiles('packages/rn-tester/Podfile.lock') }}-${{ hashfiles('packages/rn-tester/Podfile') }}-${{ inputs.hermes-version}}
+        key: v15-cocoapods-${{ github.job }}-NewArch-${{ inputs.flavor }}-${{ inputs.use-frameworks }}-${{ inputs.ruby-version }}-${{ hashfiles('packages/rn-tester/Podfile.lock') }}-${{ hashfiles('packages/rn-tester/Podfile') }}-${{ inputs.hermes-version}}
diff --git a/.github/actions/test-ios-helloworld/action.yml b/.github/actions/test-ios-helloworld/action.yml
index e85cad17a778f2..2ba71f3c3b356e 100644
--- a/.github/actions/test-ios-helloworld/action.yml
+++ b/.github/actions/test-ios-helloworld/action.yml
@@ -4,9 +4,6 @@ inputs:
   use-frameworks:
     description: The dependency building and linking strategy to use. Must be one of "StaticLibraries", "DynamicFrameworks"
     default: StaticLibraries
-  architecture:
-    description: The React Native architecture to Test. RNTester has always Fabric enabled, but we want to run integration test with the old arch setup. Must be one of "OldArch" or "NewArch"
-    default: OldArch
   ruby-version:
     description: The version of ruby that must be used
     default: 2.6.10
@@ -51,16 +48,12 @@ runs:
     - name: Print third-party folder
       shell: bash
       run: ls -lR /tmp/third-party
-    - name: Install iOS dependencies - Configuration ${{ inputs.flavor }}; New Architecture ${{ inputs.architecture }}
+    - name: Install iOS dependencies - Configuration ${{ inputs.flavor }};
       shell: bash
       run: |
         cd packages/helloworld
         args=()
 
-        if [[ ${{ inputs.architecture }} == "OldArch" ]]; then
-          args+=(--arch old)
-        fi
-
         if [[ ${{ inputs.use-frameworks }} == "DynamicFrameworks" ]]; then
           args+=(--frameworks dynamic)
         fi
diff --git a/.github/actions/test-ios-rntester/action.yml b/.github/actions/test-ios-rntester/action.yml
index 2344c7bc61904c..79f820dd34e548 100644
--- a/.github/actions/test-ios-rntester/action.yml
+++ b/.github/actions/test-ios-rntester/action.yml
@@ -4,9 +4,6 @@ inputs:
   use-frameworks:
     description: The dependency building and linking strategy to use. Must be one of "StaticLibraries", "DynamicFrameworks"
     default: StaticLibraries
-  architecture:
-    description: The React Native architecture to Test. RNTester has always Fabric enabled, but we want to run integration test with the old arch setup
-    default: NewArch
   ruby-version:
     description: The version of ruby that must be used
     default: 2.6.10
@@ -101,7 +98,6 @@ runs:
       uses: ./.github/actions/setup-xcode-build-cache
       with:
         hermes-version: ${{ inputs.hermes-version }}
-        architecture: ${{ inputs.architecture }}
         use-frameworks: ${{ inputs.use-frameworks }}
         flavor: ${{ inputs.flavor }}
         ruby-version: ${{ inputs.ruby-version }}
@@ -114,10 +110,6 @@ runs:
           export USE_FRAMEWORKS=dynamic
         fi
 
-        if [[ ${{ inputs.architecture }} == "OldArch" ]]; then
-          export RCT_NEW_ARCH_ENABLED=0
-        fi
-
         export RCT_USE_LOCAL_RN_DEP="/tmp/third-party/ReactNativeDependencies${{ inputs.flavor }}.xcframework.tar.gz"
         cd packages/rn-tester
 
@@ -162,7 +154,7 @@ runs:
       if: ${{ inputs.use-frameworks == 'StaticLibraries' && inputs.ruby-version == '2.6.10' }} # This is needed to avoid conflicts with the artifacts
       uses: actions/upload-artifact@v4.3.4
       with:
-        name: RNTesterApp-${{ inputs.architecture }}-${{ inputs.flavor }}
+        name: RNTesterApp-NewArch-${{ inputs.flavor }}
         path: ${{ env.app-path }}
     - name: Store test results
       if: ${{ inputs.run-unit-tests == 'true' }}
diff --git a/.github/workflows/test-all.yml b/.github/workflows/test-all.yml
index 5b1b0de05f87a9..a508e1cfc99d1a 100644
--- a/.github/workflows/test-all.yml
+++ b/.github/workflows/test-all.yml
@@ -168,18 +168,13 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        architecture: [NewArch, OldArch]
         flavor: [Debug, Release]
-        exclude: # We don't want to test the Old Arch in Release for E2E
-          - architecture: OldArch
-            flavor: Release
     steps:
       - name: Checkout
         uses: actions/checkout@v4
       - name: Run it
         uses: ./.github/actions/test-ios-rntester
         with:
-          architecture: ${{ matrix.architecture }}
           run-unit-tests: "false"
           use-frameworks: StaticLibraries
           hermes-version: ${{ needs.prepare_hermes_workspace.outputs.hermes-version }}
@@ -198,7 +193,6 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        architecture: [NewArch]
         flavor: [Debug, Release]
     steps:
       - name: Checkout
@@ -206,7 +200,7 @@ jobs:
       - name: Download App
         uses: actions/download-artifact@v4
         with:
-          name: RNTesterApp-${{ matrix.architecture }}-${{ matrix.flavor }}
+          name: RNTesterApp-NewArch-${{ matrix.flavor }}
           path: /tmp/RNTesterBuild/RNTester.app
       - name: Check downloaded folder content
         run: ls -lR /tmp/RNTesterBuild
@@ -232,7 +226,6 @@ jobs:
       fail-fast: false
       matrix:
         flavor: [Debug, Release]
-        architecture: [OldArch, NewArch]
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -286,10 +279,6 @@ jobs:
           cd /tmp/RNTestProject/ios
           bundle install
           NEW_ARCH_ENABLED=1
-          if [[ ${{ matrix.architecture }} == "OldArch" ]]; then
-            echo "Disable the New Architecture"
-            NEW_ARCH_ENABLED=0
-          fi
 
           export RCT_USE_LOCAL_RN_DEP=/tmp/third-party/ReactNativeDependencies${{ matrix.flavor }}.xcframework.tar.gz
           HERMES_ENGINE_TARBALL_PATH=$HERMES_PATH RCT_NEW_ARCH_ENABLED=$NEW_ARCH_ENABLED bundle exec pod install
@@ -309,7 +298,6 @@ jobs:
           maestro-flow: ./scripts/e2e/.maestro/
           flavor: ${{ matrix.flavor }}
           working-directory: /tmp/RNTestProject
-          architecture: ${{ matrix.architecture }}
 
   test_e2e_android_templateapp:
     if: ${{ github.ref == 'refs/heads/main' || contains(github.ref,  'stable') || inputs.run-e2e-tests }}
@@ -320,7 +308,6 @@ jobs:
       fail-fast: false
       matrix:
         flavor: [debug, release]
-        architecture: [OldArch, NewArch]
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -366,11 +353,6 @@ jobs:
           cd /tmp/RNTestProject
           echo "react.internal.mavenLocalRepo=$MAVEN_LOCAL" >> android/gradle.properties
 
-          if [[ ${{matrix.architecture}} == "OldArch" ]]; then
-            echo "Disabling the New Architecture"
-            sed -i 's/newArchEnabled=true/newArchEnabled=false/' android/gradle.properties
-          fi
-
           # Build
           cd android
           CAPITALIZED_FLAVOR=$(echo "${{ matrix.flavor }}" | awk '{print toupper(substr($0, 1, 1)) substr($0, 2)}')
@@ -386,7 +368,6 @@ jobs:
           install-java: 'false'
           flavor: ${{ matrix.flavor }}
           working-directory: /tmp/RNTestProject
-          architecture: ${{ matrix.architecture }}
 
   build_hermesc_linux:
     runs-on: ubuntu-latest
@@ -520,7 +501,6 @@ jobs:
       fail-fast: false
       matrix:
         flavor: [Debug, Release]
-        architecture: [NewArch, OldArch]
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -545,14 +525,11 @@ jobs:
       - name: Prepare the Helloworld application
         shell: bash
         run: node ./scripts/e2e/init-project-e2e.js --useHelloWorld --pathToLocalReactNative "$GITHUB_WORKSPACE/build/$(cat build/react-native-package-version)"
-      - name: Build the Helloworld application for ${{ matrix.flavor }} with Architecture set to ${{ matrix.architecture }}.
+      - name: Build the Helloworld application for ${{ matrix.flavor }} with Architecture set to New Architecture.
         shell: bash
         run: |
           cd packages/helloworld/android
           args=()
-          if [[ ${{ matrix.architecture }} == "OldArch" ]]; then
-            args+=(--arch old)
-          fi
           if [[ ${{ matrix.flavor }} == "Release" ]]; then
             args+=(--prod)
           fi
@@ -560,7 +537,7 @@ jobs:
       - name: Upload artifact
         uses: actions/upload-artifact@v4.3.4
         with:
-          name: helloworld-apk-${{ matrix.flavor }}-${{ matrix.architecture }}-hermes
+          name: helloworld-apk-${{ matrix.flavor }}-NewArch-hermes
           path: ./packages/helloworld/android/app/build/outputs/apk/
           compression-level: 0
 
@@ -577,7 +554,6 @@ jobs:
       - uses: ./.github/actions/test-ios-helloworld
         with:
           ruby-version: 3.2.0
-          architecture: NewArch
           flavor: Debug
           hermes-version: ${{ needs.prepare_hermes_workspace.outputs.hermes-version }}
           react-native-version: ${{ needs.prepare_hermes_workspace.outputs.react-native-version }}