diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
new file mode 100644
index 0000000..fb4b15a
--- /dev/null
+++ b/.github/workflows/coverage.yml
@@ -0,0 +1,36 @@
+name: Coverage
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+permissions:
+  contents: read
+
+jobs:
+  coverage:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
+        with:
+          # 3.10 is the real floor, see test.yml
+          python-version: "3.10"
+      - name: Install dependencies
+        run: |
+          pip install -r requirements.txt
+          pip install pytest pytest-cov
+      - name: Run tests with coverage
+        run: |
+          pytest --cov=main --cov-report=xml --cov-report=term-missing main_test.py
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@fb8b3582c8e4def4969c97caa2f19720cb33a72f # v7.0.0
+        with:
+          files: ./coverage.xml
+          flags: unittests
+          name: codecov-umbrella
+          # Hard-fail on push to main so a broken upload is visible; on PRs the
+          # report is informational and a flaky upload should not block review.
+          fail_ci_if_error: ${{ github.event_name == 'push' }}
diff --git a/.gitignore b/.gitignore
index ab3375b..f840b9c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,9 @@ venv/
 .venv/
 __pycache__/
 result.txt
+
+# pytest-cov
+.coverage
+.coverage.*
+coverage.xml
+htmlcov/
diff --git a/README.md b/README.md
index 1e4ddd9..687ad5d 100644
--- a/README.md
+++ b/README.md
@@ -5,6 +5,7 @@
 [![GitHub marketplace](https://img.shields.io/badge/Marketplace-commit--check--action-blue)](https://github.com/marketplace/actions/commit-check-action)
 [![commit-check](https://img.shields.io/badge/commit--check-enabled-brightgreen?logo=Git&logoColor=white&color=%232c9ccd)](https://github.com/commit-check/commit-check)
 [![slsa-badge](https://slsa.dev/images/gh-badge-level3.svg?color=blue)](https://github.com/commit-check/commit-check-action/blob/a2873ca0482dd505c93fb51861c953e82fd0a186/action.yml#L59-L69)
+[![codecov](https://codecov.io/gh/commit-check/commit-check-action/graph/badge.svg?token=QHUDSMJGS7)](https://codecov.io/gh/commit-check/commit-check-action)
 
 A GitHub Action for checking commit message formatting, branch naming, committer name, email, commit signoff, and more.