diff --git a/.github/workflows/phpunit-tests.yml b/.github/workflows/phpunit-tests.yml
index 420506d42265c..cafb62f4f26c4 100644
--- a/.github/workflows/phpunit-tests.yml
+++ b/.github/workflows/phpunit-tests.yml
@@ -61,7 +61,7 @@ jobs:
   #
   test-with-mysql:
     name: PHP ${{ matrix.php }}
-    uses: ./.github/workflows/reusable-phpunit-tests-v3.yml
+    uses: ./.github/workflows/reusable-phpunit-tests-v4.yml
     permissions:
       contents: read
     secrets: inherit
@@ -138,7 +138,7 @@ jobs:
   #
   test-with-mariadb:
     name: PHP ${{ matrix.php }}
-    uses: ./.github/workflows/reusable-phpunit-tests-v3.yml
+    uses: ./.github/workflows/reusable-phpunit-tests-v4.yml
     permissions:
       contents: read
     secrets: inherit
@@ -190,7 +190,7 @@ jobs:
   #
   test-innovation-releases:
     name: PHP ${{ matrix.php }}
-    uses: ./.github/workflows/reusable-phpunit-tests-v3.yml
+    uses: ./.github/workflows/reusable-phpunit-tests-v4.yml
     permissions:
       contents: read
     secrets: inherit
@@ -233,7 +233,7 @@ jobs:
   #
   html-api-test-groups:
     name: ${{ matrix.label }}
-    uses: ./.github/workflows/reusable-phpunit-tests-v3.yml
+    uses: ./.github/workflows/reusable-phpunit-tests-v4.yml
     permissions:
       contents: read
     secrets: inherit
@@ -262,7 +262,7 @@ jobs:
   #
   limited-matrix-for-forks:
     name: PHP ${{ matrix.php }}
-    uses: ./.github/workflows/reusable-phpunit-tests-v3.yml
+    uses: ./.github/workflows/reusable-phpunit-tests-v4.yml
     permissions:
       contents: read
     secrets: inherit
diff --git a/.github/workflows/reusable-phpunit-tests-v4.yml b/.github/workflows/reusable-phpunit-tests-v4.yml
new file mode 100644
index 0000000000000..59f1ae213a297
--- /dev/null
+++ b/.github/workflows/reusable-phpunit-tests-v4.yml
@@ -0,0 +1,277 @@
+##
+# A reusable workflow that runs the PHPUnit test suite with the specified configuration.
+#
+# This workflow is used by `trunk` and branches >= 6.9.
+##
+name: Run PHPUnit tests
+
+on:
+  workflow_call:
+    inputs:
+      os:
+        description: 'Operating system to run tests on'
+        required: false
+        type: 'string'
+        default: 'ubuntu-24.04'
+      php:
+        description: 'The version of PHP to use, in the format of X.Y'
+        required: true
+        type: 'string'
+      db-type:
+        description: 'Database type. Valid types are mysql and mariadb'
+        required: false
+        type: 'string'
+        default: 'mysql'
+      db-version:
+        description: 'Database version'
+        required: false
+        type: 'string'
+        default: '8.4'
+      db-innovation:
+        description: 'Whether a database software innovation release is being tested.'
+        required: false
+        type: 'boolean'
+        default: false
+      multisite:
+        description: 'Whether to run tests as multisite'
+        required: false
+        type: 'boolean'
+        default: false
+      memcached:
+        description: 'Whether to test with memcached enabled'
+        required: false
+        type: 'boolean'
+        default: false
+      phpunit-config:
+        description: 'The PHPUnit configuration file to use'
+        required: false
+        type: 'string'
+        default: 'phpunit.xml.dist'
+      phpunit-test-groups:
+        description: 'A list of test groups to run.'
+        required: false
+        type: 'string'
+        default: 'media'
+      tests-domain:
+        description: 'The domain to use for the tests'
+        required: false
+        type: 'string'
+        default: 'example.org'
+      coverage-report:
+        description: 'Whether to generate a code coverage report.'
+        required: false
+        type: boolean
+        default: false
+      report:
+        description: 'Whether to report results to WordPress.org Hosting Tests'
+        required: false
+        type: 'boolean'
+        default: false
+      allow-errors:
+        description: 'Whether to continue when test errors occur.'
+        required: false
+        type: boolean
+        default: false
+      install-imagemagick:
+        description: 'Whether to install ImageMagick.'
+        required: false
+        type: boolean
+        default: true
+    secrets:
+      CODECOV_TOKEN:
+        description: 'The Codecov token required for uploading reports.'
+        required: false
+      WPT_REPORT_API_KEY:
+        description: 'The WordPress.org Hosting Tests API key.'
+        required: false
+
+env:
+  LOCAL_PHP_MEMCACHED: ${{ inputs.memcached }}
+  PHPUNIT_CONFIG: ${{ inputs.phpunit-config }}
+  PUPPETEER_SKIP_DOWNLOAD: ${{ true }}
+
+jobs:
+  # Runs the PHPUnit tests for WordPress.
+  #
+  # Performs the following steps:
+  # - Sets environment variables.
+  # - Checks out the repository.
+  # - Sets up Node.js.
+  # - Sets up PHP.
+  # - Installs Composer dependencies.
+  # - Installs npm dependencies
+  # - Logs general debug information about the runner.
+  # - Logs Docker debug information (about the Docker installation within the runner).
+  # - Starts the WordPress Docker container.
+  # - Logs the running Docker containers.
+  # - Logs debug information about what's installed within the WordPress Docker containers.
+  # - Install WordPress within the Docker container.
+  # - Run the PHPUnit tests.
+  # - Upload the code coverage report to Codecov.io.
+  # - Upload the HTML code coverage report as an artifact.
+  # - Ensures version-controlled files are not modified or deleted.
+  # - Checks out the WordPress Test reporter repository.
+  # - Submit the test results to the WordPress.org host test results.
+  phpunit-tests:
+    name: ${{ ( inputs.phpunit-test-groups || inputs.coverage-report ) && format( 'PHP {0} with ', inputs.php ) || '' }} ${{ 'mariadb' == inputs.db-type && 'MariaDB' || 'MySQL' }} ${{ inputs.db-version }}${{ inputs.multisite && ' multisite' || '' }}${{ inputs.db-innovation && ' (innovation release)' || '' }}${{ inputs.memcached && ' with memcached' || '' }}${{ inputs.report && ' (test reporting enabled)' || '' }} ${{ 'example.org' != inputs.tests-domain && inputs.tests-domain || '' }}
+    runs-on: ${{ inputs.os }}
+    timeout-minutes: ${{ inputs.coverage-report && 120 || inputs.php == '8.4' && 30 || 20 }}
+    permissions:
+      contents: read
+
+    services:
+      database:
+        image: ${{ inputs.db-type }}:${{ inputs.db-version }}
+        ports:
+          - 3306
+        env:
+          MYSQL_ROOT_PASSWORD: password
+          MYSQL_DATABASE: wordpress_develop_tests
+        options: >-
+          --health-cmd="${{ inputs.db-type == 'mariadb' && ! contains( fromJSON( '["5.5", "10.0", "10.1", "10.2", "10.3"]' ), inputs.db-version ) && 'mariadb-admin ping' || 'mysqladmin ping' }}"
+          --health-interval="30s"
+          --health-timeout="10s"
+          --health-retries="5"
+          ${{ inputs.db-type == 'mysql' && contains( fromJSON('["7.2", "7.3"]'), inputs.php ) && inputs.db-version == '8.4' && '--authentication-policy=mysql_native_password' || '' }}
+          ${{ inputs.db-type == 'mysql' && contains( fromJSON('["7.2", "7.3"]'), inputs.php ) && inputs.db-version != '8.4' && '--default-authentication-plugin=mysql_native_password' || '' }}
+
+    steps:
+      - name: Install ImageMagick with AVIF support
+        if: ${{ inputs.install-imagemagick }}
+        run: |
+          sudo apt-get remove --purge -y imagemagick imagemagick-6-common libmagickcore-6* libmagickwand-6*
+          sudo apt-get autoremove -y
+          which magick || echo "ImageMagick removed"
+          sudo apt-get update
+          sudo apt-get install -y \
+          build-essential pkg-config autoconf automake libtool \
+          libjpeg-dev libpng-dev libtiff-dev zlib1g-dev \
+          libheif-dev libaom-dev libdav1d-dev libde265-dev
+          curl -fsSL https://imagemagick.org/archive/ImageMagick.tar.gz | tar xz
+          cd ImageMagick-*
+          ./configure --with-heic=yes
+          make -j"$(nproc)"
+          sudo make install
+          sudo ldconfig
+
+      - name: Confirm AVIF support
+        run: magick -version | grep Delegates
+
+      - name: Confirm image format support
+        run: magick -list format
+
+      - name: Log PHP debugging information
+        run: php -i
+
+      - name: Checkout repository
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          show-progress: ${{ runner.debug == '1' && 'true' || 'false' }}
+          persist-credentials: false
+
+      - name: Set up Node.js
+        uses: actions/setup-node@cdca7365b2dadb8aad0a33bc7601856ffabcc48e # v4.3.0
+        with:
+          node-version-file: '.nvmrc'
+          cache: npm
+
+      - name: Set up PHP
+        uses: shivammathur/setup-php@20529878ed81ef8e78ddf08b480401e6101a850f # v2.35.3
+        with:
+          php-version: '${{ inputs.php }}'
+          coverage: ${{ inputs.coverage-report && 'xdebug' || 'none' }}
+          tools: wp-cli
+
+      # Since Composer dependencies are installed using `composer update` and no lock file is in version control,
+      # passing a custom cache suffix ensures that the cache is flushed at least once per week.
+      - name: Install Composer dependencies
+        uses: ramsey/composer-install@3cf229dc2919194e9e36783941438d17239e8520 # v3.1.1
+        with:
+          custom-cache-suffix: $(/bin/date -u --date='last Mon' "+%F")
+
+      - name: Install npm dependencies
+        run: npm ci
+
+      - name: General debug information
+        run: |
+          npm --version
+          node --version
+          curl --version
+          git --version
+          composer --version
+          locale -a
+
+      - name: Create wp-tests-config.php file
+        run: cp wp-tests-config-sample.php wp-tests-config.php
+
+      - name: Change DB_NAME value
+        run: wp config set DB_NAME wordpress_develop_tests --config-file=wp-tests-config.php
+
+      - name: Change DB_USER value
+        run: wp config set DB_USER root --config-file=wp-tests-config.php
+
+      - name: Change DB_PASSWORD value
+        run: wp config set DB_PASSWORD password --config-file=wp-tests-config.php
+
+      - name: Change DB_HOST value
+        run: wp config set DB_HOST 127.0.0.1:${{ job.services.database.ports['3306'] }} --config-file=wp-tests-config.php
+
+      - name: Run PHPUnit tests${{ inputs.phpunit-test-groups && format( ' ({0} groups)', inputs.phpunit-test-groups ) || '' }}${{ inputs.coverage-report && ' with coverage report' || '' }}
+        continue-on-error: ${{ inputs.allow-errors }}
+        run: ./vendor/bin/phpunit --verbose -c ${{ env.PHPUNIT_CONFIG }}${{ inputs.phpunit-test-groups && format( ' --group {0}', inputs.phpunit-test-groups ) || '' }}${{ inputs.coverage-report && format( ' --coverage-clover wp-code-coverage-{0}-{1}.xml --coverage-html wp-code-coverage-{0}-{1}', ( inputs.multisite && 'multisite' || 'single' ), github.sha ) || '' }}
+
+      - name: Run AJAX tests
+        if: ${{ ! inputs.phpunit-test-groups && ! inputs.coverage-report }}
+        continue-on-error: ${{ inputs.allow-errors }}
+        run: ./vendor/bin/phpunit --verbose -c ${{ env.PHPUNIT_CONFIG }} --group ajax
+
+      - name: Run ms-files tests as a multisite install
+        if: ${{ inputs.multisite && ! inputs.phpunit-test-groups && ! inputs.coverage-report }}
+        continue-on-error: ${{ inputs.allow-errors }}
+        run: ./vendor/bin/phpunit --verbose -c ${{ env.PHPUNIT_CONFIG }} --group ms-files
+
+      - name: Run external HTTP tests
+        if: ${{ ! inputs.multisite && ! inputs.phpunit-test-groups && ! inputs.coverage-report }}
+        continue-on-error: ${{ inputs.allow-errors }}
+        run: ./vendor/bin/phpunit --verbose -c ${{ env.PHPUNIT_CONFIG }} --group external-http
+
+      # __fakegroup__ is excluded to force PHPUnit to ignore the <exclude> settings in phpunit.xml.dist.
+      - name: Run (Xdebug) tests
+        if: ${{ inputs.php != '8.4' && ! inputs.phpunit-test-groups && ! inputs.coverage-report }}
+        continue-on-error: ${{ inputs.allow-errors }}
+        run: LOCAL_PHP_XDEBUG=true node ./tools/local-env/scripts/docker.js run php ./vendor/bin/phpunit -v --group xdebug --exclude-group __fakegroup__
+
+      - name: Upload test coverage report to Codecov
+        if: ${{ inputs.coverage-report }}
+        uses: codecov/codecov-action@18283e04ce6e62d37312384ff67231eb8fd56d24 # v5.4.3
+        with:
+          token: ${{ secrets.CODECOV_TOKEN }}
+          files: wp-code-coverage${{ inputs.multisite && '-multisite' || '-single' }}-${{ github.sha }}.xml
+          flags: ${{ inputs.multisite && 'multisite' || 'single' }},php
+          fail_ci_if_error: true
+
+      - name: Upload HTML coverage report as artifact
+        if: ${{ inputs.coverage-report }}
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
+        with:
+          name: wp-code-coverage${{ inputs.multisite && '-multisite' || '-single' }}-${{ github.sha }}
+          path: wp-code-coverage${{ inputs.multisite && '-multisite' || '-single' }}-${{ github.sha }}
+          overwrite: true
+
+      - name: Ensure version-controlled files are not modified or deleted
+        run: git diff --exit-code
+
+      - name: Checkout the WordPress Test Reporter
+        if: ${{ github.ref == 'refs/heads/trunk' && inputs.report }}
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+        with:
+          repository: 'WordPress/phpunit-test-runner'
+          path: 'test-runner'
+          show-progress: ${{ runner.debug == '1' && 'true' || 'false' }}
+          persist-credentials: false
+
+      - name: Submit test results to the WordPress.org host test results
+        if: ${{ github.ref == 'refs/heads/trunk' && inputs.report }}
+        env:
+          WPT_REPORT_API_KEY: "${{ secrets.WPT_REPORT_API_KEY }}"
+        run: docker compose run --rm -e WPT_REPORT_API_KEY -e WPT_PREPARE_DIR=/var/www -e WPT_TEST_DIR=/var/www php php test-runner/report.php