diff --git a/.github/workflows/coding-standards.yml b/.github/workflows/coding-standards.yml
index 8f1e9fe701330..d579368eeb079 100644
--- a/.github/workflows/coding-standards.yml
+++ b/.github/workflows/coding-standards.yml
@@ -89,6 +89,7 @@ jobs:
       SLACK_GHA_CANCELLED_WEBHOOK: ${{ secrets.SLACK_GHA_CANCELLED_WEBHOOK }}
       SLACK_GHA_FIXED_WEBHOOK: ${{ secrets.SLACK_GHA_FIXED_WEBHOOK }}
       SLACK_GHA_FAILURE_WEBHOOK: ${{ secrets.SLACK_GHA_FAILURE_WEBHOOK }}
+      SLACK_GHA_TIMEOUT_WEBHOOK: ${{ secrets.SLACK_GHA_TIMEOUT_WEBHOOK }}
 
   failed-workflow:
     name: Failed workflow tasks
diff --git a/.github/workflows/end-to-end-tests.yml b/.github/workflows/end-to-end-tests.yml
index d91b6512f4b49..f2eb5abb83ddb 100644
--- a/.github/workflows/end-to-end-tests.yml
+++ b/.github/workflows/end-to-end-tests.yml
@@ -89,6 +89,7 @@ jobs:
       SLACK_GHA_CANCELLED_WEBHOOK: ${{ secrets.SLACK_GHA_CANCELLED_WEBHOOK }}
       SLACK_GHA_FIXED_WEBHOOK: ${{ secrets.SLACK_GHA_FIXED_WEBHOOK }}
       SLACK_GHA_FAILURE_WEBHOOK: ${{ secrets.SLACK_GHA_FAILURE_WEBHOOK }}
+      SLACK_GHA_TIMEOUT_WEBHOOK: ${{ secrets.SLACK_GHA_TIMEOUT_WEBHOOK }}
 
   failed-workflow:
     name: Failed workflow tasks
diff --git a/.github/workflows/install-testing.yml b/.github/workflows/install-testing.yml
index 140e5f679701a..d69dc103d2d3a 100644
--- a/.github/workflows/install-testing.yml
+++ b/.github/workflows/install-testing.yml
@@ -152,6 +152,7 @@ jobs:
       SLACK_GHA_CANCELLED_WEBHOOK: ${{ secrets.SLACK_GHA_CANCELLED_WEBHOOK }}
       SLACK_GHA_FIXED_WEBHOOK: ${{ secrets.SLACK_GHA_FIXED_WEBHOOK }}
       SLACK_GHA_FAILURE_WEBHOOK: ${{ secrets.SLACK_GHA_FAILURE_WEBHOOK }}
+      SLACK_GHA_TIMEOUT_WEBHOOK: ${{ secrets.SLACK_GHA_TIMEOUT_WEBHOOK }}
 
   failed-workflow:
     name: Failed workflow tasks
diff --git a/.github/workflows/javascript-tests.yml b/.github/workflows/javascript-tests.yml
index 8b1241038773d..08a118e4a4056 100644
--- a/.github/workflows/javascript-tests.yml
+++ b/.github/workflows/javascript-tests.yml
@@ -77,6 +77,7 @@ jobs:
       SLACK_GHA_CANCELLED_WEBHOOK: ${{ secrets.SLACK_GHA_CANCELLED_WEBHOOK }}
       SLACK_GHA_FIXED_WEBHOOK: ${{ secrets.SLACK_GHA_FIXED_WEBHOOK }}
       SLACK_GHA_FAILURE_WEBHOOK: ${{ secrets.SLACK_GHA_FAILURE_WEBHOOK }}
+      SLACK_GHA_TIMEOUT_WEBHOOK: ${{ secrets.SLACK_GHA_TIMEOUT_WEBHOOK }}
 
   failed-workflow:
     name: Failed workflow tasks
diff --git a/.github/workflows/javascript-type-checking.yml b/.github/workflows/javascript-type-checking.yml
index 65561cabbb1e1..4983e0c619ec8 100644
--- a/.github/workflows/javascript-type-checking.yml
+++ b/.github/workflows/javascript-type-checking.yml
@@ -70,6 +70,7 @@ jobs:
       SLACK_GHA_CANCELLED_WEBHOOK: ${{ secrets.SLACK_GHA_CANCELLED_WEBHOOK }}
       SLACK_GHA_FIXED_WEBHOOK: ${{ secrets.SLACK_GHA_FIXED_WEBHOOK }}
       SLACK_GHA_FAILURE_WEBHOOK: ${{ secrets.SLACK_GHA_FAILURE_WEBHOOK }}
+      SLACK_GHA_TIMEOUT_WEBHOOK: ${{ secrets.SLACK_GHA_TIMEOUT_WEBHOOK }}
 
   failed-workflow:
     name: Failed workflow tasks
diff --git a/.github/workflows/local-docker-environment.yml b/.github/workflows/local-docker-environment.yml
index 856db171726b6..0f88d54ff4eb8 100644
--- a/.github/workflows/local-docker-environment.yml
+++ b/.github/workflows/local-docker-environment.yml
@@ -135,6 +135,7 @@ jobs:
       SLACK_GHA_CANCELLED_WEBHOOK: ${{ secrets.SLACK_GHA_CANCELLED_WEBHOOK }}
       SLACK_GHA_FIXED_WEBHOOK: ${{ secrets.SLACK_GHA_FIXED_WEBHOOK }}
       SLACK_GHA_FAILURE_WEBHOOK: ${{ secrets.SLACK_GHA_FAILURE_WEBHOOK }}
+      SLACK_GHA_TIMEOUT_WEBHOOK: ${{ secrets.SLACK_GHA_TIMEOUT_WEBHOOK }}
 
   failed-workflow:
     name: Failed workflow tasks
diff --git a/.github/workflows/performance.yml b/.github/workflows/performance.yml
index ef02c51101557..22a3a27392859 100644
--- a/.github/workflows/performance.yml
+++ b/.github/workflows/performance.yml
@@ -153,6 +153,7 @@ jobs:
       SLACK_GHA_CANCELLED_WEBHOOK: ${{ secrets.SLACK_GHA_CANCELLED_WEBHOOK }}
       SLACK_GHA_FIXED_WEBHOOK: ${{ secrets.SLACK_GHA_FIXED_WEBHOOK }}
       SLACK_GHA_FAILURE_WEBHOOK: ${{ secrets.SLACK_GHA_FAILURE_WEBHOOK }}
+      SLACK_GHA_TIMEOUT_WEBHOOK: ${{ secrets.SLACK_GHA_TIMEOUT_WEBHOOK }}
 
   failed-workflow:
     name: Failed workflow tasks
diff --git a/.github/workflows/php-compatibility.yml b/.github/workflows/php-compatibility.yml
index 4bae7e0a381b0..37de91a73b24b 100644
--- a/.github/workflows/php-compatibility.yml
+++ b/.github/workflows/php-compatibility.yml
@@ -66,6 +66,7 @@ jobs:
       SLACK_GHA_CANCELLED_WEBHOOK: ${{ secrets.SLACK_GHA_CANCELLED_WEBHOOK }}
       SLACK_GHA_FIXED_WEBHOOK: ${{ secrets.SLACK_GHA_FIXED_WEBHOOK }}
       SLACK_GHA_FAILURE_WEBHOOK: ${{ secrets.SLACK_GHA_FAILURE_WEBHOOK }}
+      SLACK_GHA_TIMEOUT_WEBHOOK: ${{ secrets.SLACK_GHA_TIMEOUT_WEBHOOK }}
 
   failed-workflow:
     name: Failed workflow tasks
diff --git a/.github/workflows/phpstan-static-analysis.yml b/.github/workflows/phpstan-static-analysis.yml
index 6a26c75b16525..a07ee13e16467 100644
--- a/.github/workflows/phpstan-static-analysis.yml
+++ b/.github/workflows/phpstan-static-analysis.yml
@@ -66,6 +66,7 @@ jobs:
       SLACK_GHA_CANCELLED_WEBHOOK: ${{ secrets.SLACK_GHA_CANCELLED_WEBHOOK }}
       SLACK_GHA_FIXED_WEBHOOK: ${{ secrets.SLACK_GHA_FIXED_WEBHOOK }}
       SLACK_GHA_FAILURE_WEBHOOK: ${{ secrets.SLACK_GHA_FAILURE_WEBHOOK }}
+      SLACK_GHA_TIMEOUT_WEBHOOK: ${{ secrets.SLACK_GHA_TIMEOUT_WEBHOOK }}
 
   failed-workflow:
     name: Failed workflow tasks
diff --git a/.github/workflows/phpunit-tests.yml b/.github/workflows/phpunit-tests.yml
index f0f1282f73a93..30cf72bc606ae 100644
--- a/.github/workflows/phpunit-tests.yml
+++ b/.github/workflows/phpunit-tests.yml
@@ -411,6 +411,7 @@ jobs:
       SLACK_GHA_CANCELLED_WEBHOOK: ${{ secrets.SLACK_GHA_CANCELLED_WEBHOOK }}
       SLACK_GHA_FIXED_WEBHOOK: ${{ secrets.SLACK_GHA_FIXED_WEBHOOK }}
       SLACK_GHA_FAILURE_WEBHOOK: ${{ secrets.SLACK_GHA_FAILURE_WEBHOOK }}
+      SLACK_GHA_TIMEOUT_WEBHOOK: ${{ secrets.SLACK_GHA_TIMEOUT_WEBHOOK }}
 
   failed-workflow:
     name: Failed workflow tasks
diff --git a/.github/workflows/slack-notifications.yml b/.github/workflows/slack-notifications.yml
index 0877405409e83..4b4dfc831aaeb 100644
--- a/.github/workflows/slack-notifications.yml
+++ b/.github/workflows/slack-notifications.yml
@@ -25,6 +25,9 @@ on:
       SLACK_GHA_FAILURE_WEBHOOK:
         description: 'The Slack webhook URL for a failed build.'
         required: true
+      SLACK_GHA_TIMEOUT_WEBHOOK:
+        description: 'The Slack webhook URL for a timed out build.'
+        required: true
 
 # Disable permissions for all available scopes by default.
 # Any needed permissions should be configured at the job level.
@@ -55,6 +58,7 @@ jobs:
     if: ${{ github.repository == 'WordPress/wordpress-develop' && github.event.workflow_run.event != 'pull_request' }}
     outputs:
       previous_conclusion: ${{ steps.previous-attempt-result.outputs.result }}
+      timed_out: ${{ steps.timeout-check.outputs.result }}
       payload: ${{ steps.create-payload.outputs.payload }}
 
     steps:
@@ -128,6 +132,25 @@ jobs:
         env:
           CALLING_STATUS: ${{ inputs.calling_status }}
 
+      # The REST API exposes a distinct `timed_out` job conclusion that is unavailable through workflow contexts.
+      - name: Determine whether the workflow timed out
+        id: timeout-check
+        uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9.0.0
+        if: ${{ inputs.calling_status == 'cancelled' }}
+        with:
+          retries: 2
+          retry-exempt-status-codes: 418
+          result-encoding: string
+          script: |
+            const jobs = await github.paginate( github.rest.actions.listJobsForWorkflowRunAttempt, {
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              run_id: `${context.runId}`,
+              attempt_number: Number( process.env.GITHUB_RUN_ATTEMPT ),
+            }, ( response ) => response.data.jobs );
+
+            return jobs.some( ( job ) => job.conclusion === 'timed_out' ) ? 'true' : 'false';
+
       - name: Get the commit message
         id: current-commit-message
         uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9.0.0
@@ -211,14 +234,13 @@ jobs:
           webhook: ${{ secrets.SLACK_GHA_SUCCESS_WEBHOOK }}
           payload: ${{ needs.prepare.outputs.payload }}
 
-  # Posts notifications when a workflow is cancelled.
   cancelled:
     name: Cancelled notifications
     permissions: {}
     runs-on: ubuntu-24.04
     timeout-minutes: 20
     needs: [ prepare ]
-    if: ${{ inputs.calling_status == 'cancelled' && github.run_attempt == 2 || cancelled() }}
+    if: ${{ ( inputs.calling_status == 'cancelled' && github.run_attempt == 2 && needs.prepare.outputs.timed_out != 'true' ) || cancelled() }}
 
     steps:
       - name: Post cancelled notifications to Slack
@@ -227,3 +249,19 @@ jobs:
           webhook-type: webhook-trigger
           webhook: ${{ secrets.SLACK_GHA_CANCELLED_WEBHOOK }}
           payload: ${{ needs.prepare.outputs.payload }}
+
+  timeout:
+    name: Timeout notifications
+    permissions: {}
+    runs-on: ubuntu-24.04
+    timeout-minutes: 20
+    needs: [ prepare ]
+    if: ${{ inputs.calling_status == 'cancelled' && github.run_attempt == 2 && needs.prepare.outputs.timed_out == 'true' }}
+
+    steps:
+      - name: Post timeout notifications to Slack
+        uses: slackapi/slack-github-action@45a88b9581bfab2566dc881e2cd66d334e621e2c # v3.0.3
+        with:
+          webhook-type: webhook-trigger
+          webhook: ${{ secrets.SLACK_GHA_TIMEOUT_WEBHOOK }}
+          payload: ${{ needs.prepare.outputs.payload }}
diff --git a/.github/workflows/test-and-zip-default-themes.yml b/.github/workflows/test-and-zip-default-themes.yml
index 30c15408f9736..0464a1652d36b 100644
--- a/.github/workflows/test-and-zip-default-themes.yml
+++ b/.github/workflows/test-and-zip-default-themes.yml
@@ -284,6 +284,7 @@ jobs:
       SLACK_GHA_CANCELLED_WEBHOOK: ${{ secrets.SLACK_GHA_CANCELLED_WEBHOOK }}
       SLACK_GHA_FIXED_WEBHOOK: ${{ secrets.SLACK_GHA_FIXED_WEBHOOK }}
       SLACK_GHA_FAILURE_WEBHOOK: ${{ secrets.SLACK_GHA_FAILURE_WEBHOOK }}
+      SLACK_GHA_TIMEOUT_WEBHOOK: ${{ secrets.SLACK_GHA_TIMEOUT_WEBHOOK }}
 
   failed-workflow:
     name: Failed workflow tasks
diff --git a/.github/workflows/test-build-processes.yml b/.github/workflows/test-build-processes.yml
index cd32d99cacb1f..ab3bea392cef8 100644
--- a/.github/workflows/test-build-processes.yml
+++ b/.github/workflows/test-build-processes.yml
@@ -118,6 +118,7 @@ jobs:
       SLACK_GHA_CANCELLED_WEBHOOK: ${{ secrets.SLACK_GHA_CANCELLED_WEBHOOK }}
       SLACK_GHA_FIXED_WEBHOOK: ${{ secrets.SLACK_GHA_FIXED_WEBHOOK }}
       SLACK_GHA_FAILURE_WEBHOOK: ${{ secrets.SLACK_GHA_FAILURE_WEBHOOK }}
+      SLACK_GHA_TIMEOUT_WEBHOOK: ${{ secrets.SLACK_GHA_TIMEOUT_WEBHOOK }}
 
   failed-workflow:
     name: Failed workflow tasks
diff --git a/.github/workflows/test-coverage.yml b/.github/workflows/test-coverage.yml
index 191445ba7167c..94f57628254c3 100644
--- a/.github/workflows/test-coverage.yml
+++ b/.github/workflows/test-coverage.yml
@@ -97,6 +97,7 @@ jobs:
       SLACK_GHA_CANCELLED_WEBHOOK: ${{ secrets.SLACK_GHA_CANCELLED_WEBHOOK }}
       SLACK_GHA_FIXED_WEBHOOK: ${{ secrets.SLACK_GHA_FIXED_WEBHOOK }}
       SLACK_GHA_FAILURE_WEBHOOK: ${{ secrets.SLACK_GHA_FAILURE_WEBHOOK }}
+      SLACK_GHA_TIMEOUT_WEBHOOK: ${{ secrets.SLACK_GHA_TIMEOUT_WEBHOOK }}
 
   failed-workflow:
     name: Failed workflow tasks
diff --git a/.github/workflows/test-old-branches.yml b/.github/workflows/test-old-branches.yml
index b5bef1b88c0bc..7094550485c4f 100644
--- a/.github/workflows/test-old-branches.yml
+++ b/.github/workflows/test-old-branches.yml
@@ -158,3 +158,4 @@ jobs:
       SLACK_GHA_CANCELLED_WEBHOOK: ${{ secrets.SLACK_GHA_CANCELLED_WEBHOOK }}
       SLACK_GHA_FIXED_WEBHOOK: ${{ secrets.SLACK_GHA_FIXED_WEBHOOK }}
       SLACK_GHA_FAILURE_WEBHOOK: ${{ secrets.SLACK_GHA_FAILURE_WEBHOOK }}
+      SLACK_GHA_TIMEOUT_WEBHOOK: ${{ secrets.SLACK_GHA_TIMEOUT_WEBHOOK }}
diff --git a/.github/workflows/upgrade-develop-testing.yml b/.github/workflows/upgrade-develop-testing.yml
index f14736af874a1..4147d3f054b8b 100644
--- a/.github/workflows/upgrade-develop-testing.yml
+++ b/.github/workflows/upgrade-develop-testing.yml
@@ -140,6 +140,7 @@ jobs:
       SLACK_GHA_CANCELLED_WEBHOOK: ${{ secrets.SLACK_GHA_CANCELLED_WEBHOOK }}
       SLACK_GHA_FIXED_WEBHOOK: ${{ secrets.SLACK_GHA_FIXED_WEBHOOK }}
       SLACK_GHA_FAILURE_WEBHOOK: ${{ secrets.SLACK_GHA_FAILURE_WEBHOOK }}
+      SLACK_GHA_TIMEOUT_WEBHOOK: ${{ secrets.SLACK_GHA_TIMEOUT_WEBHOOK }}
 
   failed-workflow:
     name: Failed workflow tasks
diff --git a/.github/workflows/upgrade-testing.yml b/.github/workflows/upgrade-testing.yml
index 9a9c239e3093d..0d89c062f3b3b 100644
--- a/.github/workflows/upgrade-testing.yml
+++ b/.github/workflows/upgrade-testing.yml
@@ -206,6 +206,7 @@ jobs:
       SLACK_GHA_CANCELLED_WEBHOOK: ${{ secrets.SLACK_GHA_CANCELLED_WEBHOOK }}
       SLACK_GHA_FIXED_WEBHOOK: ${{ secrets.SLACK_GHA_FIXED_WEBHOOK }}
       SLACK_GHA_FAILURE_WEBHOOK: ${{ secrets.SLACK_GHA_FAILURE_WEBHOOK }}
+      SLACK_GHA_TIMEOUT_WEBHOOK: ${{ secrets.SLACK_GHA_TIMEOUT_WEBHOOK }}
 
   failed-workflow:
     name: Failed workflow tasks
diff --git a/.github/workflows/workflow-lint.yml b/.github/workflows/workflow-lint.yml
index b2d5c2638e7b4..1ef050f1b9b92 100644
--- a/.github/workflows/workflow-lint.yml
+++ b/.github/workflows/workflow-lint.yml
@@ -61,6 +61,7 @@ jobs:
       SLACK_GHA_CANCELLED_WEBHOOK: ${{ secrets.SLACK_GHA_CANCELLED_WEBHOOK }}
       SLACK_GHA_FIXED_WEBHOOK: ${{ secrets.SLACK_GHA_FIXED_WEBHOOK }}
       SLACK_GHA_FAILURE_WEBHOOK: ${{ secrets.SLACK_GHA_FAILURE_WEBHOOK }}
+      SLACK_GHA_TIMEOUT_WEBHOOK: ${{ secrets.SLACK_GHA_TIMEOUT_WEBHOOK }}
 
   failed-workflow:
     name: Failed workflow tasks