diff --git a/scripts/postversion-commit.js b/scripts/postversion-commit.js
new file mode 100644
index 0000000..2482221
--- /dev/null
+++ b/scripts/postversion-commit.js
@@ -0,0 +1,27 @@
+import {execSync} from 'node:child_process';
+import assert from 'node:assert/strict';
+
+/**
+ * Utility for committing and tagging a release commit in
+ * git, called as part of the `yarn postversion` script.
+ */
+
+const version = process.env.VERSION;
+
+assert.match(
+  version,
+  /^v\d+\.\d+\.\d+[a-zA-Z0-9\._-]*$/,
+  'Missing or invalid process.env.VERSION'
+);
+
+const currentBranch = execSync('git rev-parse --abbrev-ref HEAD')
+  .toString()
+  .trim();
+
+if (currentBranch === 'main') {
+  execSync(`git checkout -b 'release/${version}'`);
+}
+
+execSync('git add -u');
+execSync(`git commit -m 'chore(release): ${version}'`);
+execSync(`git tag -a ${version} -m ${version}`);