diff --git a/.github/workflows/merge.yaml b/.github/workflows/merge.yaml
index ffb8dd6..10e67fd 100644
--- a/.github/workflows/merge.yaml
+++ b/.github/workflows/merge.yaml
@@ -24,23 +24,10 @@ jobs:
 
     steps:
       - name: "Request review from @ergebnis-bot"
-        uses: "actions/github-script@v5"
+        uses: "ergebnis/.github/actions/github/pull-request/request-review@main"
         with:
           github-token: "${{ secrets.ERGEBNIS_BOT_TOKEN }}"
-          script: |
-            const pullRequest = context.payload.workflow_run.pull_requests[0];
-            const repository = context.repo;
-
-            const reviewers = [
-              "ergebnis-bot",
-            ]
-
-            await github.rest.pulls.requestReviewers({
-              owner: repository.owner,
-              repo: repository.repo,
-              pull_number: pullRequest.number,
-              reviewers: reviewers,
-            });
+          reviewer: "ergebnis-bot"
 
       - name: "Assign @ergebnis-bot"
         uses: "ergebnis/.github/actions/github/pull-request/add-assignee@main"
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2d18b47..486683c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@ For a full diff see [`1.2.1...main`][1.2.1...main].
 - Added composite action `github/pull-request/merge` ([#64]), by [@localheinz]
 - Added composite action `github/pull-request/add-label-based-on-branch-name` ([#67]), by [@localheinz]
 - Added composite action `github/release/create` ([#72]), by [@localheinz]
+- Added composite action `github/pull-request/request-review` ([#73]), by [@localheinz]
 
 ## [`1.2.1`][1.2.1]
 
@@ -68,5 +69,6 @@ For a full diff see [`1.0.0...main`][1.0.0...main].
 [#64]: https://github.com/ergebnis/.github/pull/64
 [#67]: https://github.com/ergebnis/.github/pull/67
 [#72]: https://github.com/ergebnis/.github/pull/72
+[#73]: https://github.com/ergebnis/.github/pull/73
 
 [@localheinz]: https://github.com/localheinz
diff --git a/actions/github/pull-request/request-review/action.yaml b/actions/github/pull-request/request-review/action.yaml
new file mode 100644
index 0000000..bbaee76
--- /dev/null
+++ b/actions/github/pull-request/request-review/action.yaml
@@ -0,0 +1,72 @@
+# https://docs.github.com/en/actions/creating-actions/creating-a-composite-action
+# https://docs.github.com/en/actions/creating-actions/metadata-syntax-for-github-actions#inputs
+# https://docs.github.com/en/actions/creating-actions/metadata-syntax-for-github-actions#runs-for-composite-run-steps-actions
+# https://docs.github.com/en/rest/reference/pulls#request-reviewers-for-a-pull-request
+# https://docs.github.com/en/developers/webhooks-and-events/webhooks/webhook-events-and-payloads#pull_request
+# https://docs.github.com/en/developers/webhooks-and-events/webhooks/webhook-events-and-payloads#workflow_run
+
+name: "Request review from reviewer for pull request"
+
+description: "Requests a review from a reviewer for a pull request"
+
+inputs:
+  github-token:
+    description: "GitHub token of a user with permission to request reviewers for a pull request"
+    required: true
+  reviewer:
+    description: "Username of user to request review from for a pull request"
+    required: true
+
+runs:
+  using: "composite"
+
+  steps:
+    - name: "Determine pull request number"
+      uses: "actions/github-script@v5"
+      with:
+        github-token: "${{ inputs.github-token }}"
+        script: |
+          if (
+            context.eventName == 'pull_request' ||) {
+            context.eventName == 'pull_request_target'
+          ) {
+            core.exportVariable("PULL_REQUEST_NUMBER", context.payload.pull_request.number);
+
+            return;
+          }
+
+          if (context.eventName == 'workflow_run') {
+            core.exportVariable("PULL_REQUEST_NUMBER", context.payload.workflow_run.pull_requests[0].number);
+
+            return;
+          }
+
+          core.setFailed(`Unable to determine the pull request number for event "${context.eventName}"`);
+
+    - name: "Request reviewer"
+      uses: "actions/github-script@v5"
+      env:
+        REVIEWER: "${{ inputs.reviewer }}"
+      with:
+        github-token: "${{ inputs.github-token }}"
+        script: |
+          if (!process.env.PULL_REQUEST_NUMBER) {
+            core.setFailed("The environment variable PULL_REQUEST_NUMBER is not defined.");
+
+            return;
+          }
+
+          const reviewers = [
+            process.env.REVIEWER,
+          ];
+
+          try {
+            await github.rest.pulls.requestReviewers({
+              owner: context.repo.owner,
+              pull_number: process.env.PULL_REQUEST_NUMBER,
+              repo: context.repo.repo,
+              reviewers: reviewers,
+            });
+          } catch (error) {
+            core.setFailed(error.message);
+          }