diff --git a/.github/workflows/update-bundle.yml b/.github/workflows/update-bundle.yml
index d7d90b749a..36503a64d4 100644
--- a/.github/workflows/update-bundle.yml
+++ b/.github/workflows/update-bundle.yml
@@ -113,11 +113,12 @@ jobs:
           echo "CLI_VERSION=$cli_version" | tee -a "$GITHUB_ENV"
           echo "PR_URL=$pr_url" | tee -a "$GITHUB_ENV"
 
-      - name: Create changelog note
+      - name: Create changenote
         run: |
           npx tsx pr-checks/bundle-changelog.ts
 
-      - name: Push changelog note
+      - name: Push changenote
         run: |
-          git commit -am "Add changelog note"
+          git add unreleased-change-notes
+          git commit -m "Add changenote"
           git push
diff --git a/pr-checks/bundle-changelog.test.ts b/pr-checks/bundle-changelog.test.ts
index fad06826a6..448851507d 100644
--- a/pr-checks/bundle-changelog.test.ts
+++ b/pr-checks/bundle-changelog.test.ts
@@ -10,17 +10,13 @@ import { afterEach, beforeEach, describe, it } from "node:test";
 
 import {
   CLI_VERSION_ENV_VAR,
+  getChangenote,
   getCLIVersion,
   getPRNumber,
   getPRUrl,
   PR_URL_ENV_VAR,
-  updateChangelog,
 } from "./bundle-changelog";
-import {
-  EMPTY_CHANGELOG,
-  NO_CHANGES_STR,
-  UNRELEASED_PLACEHOLDER,
-} from "./changelog";
+import { isValidChangenoteContent } from "./changelog/validate";
 
 let testDir: string;
 
@@ -85,58 +81,15 @@ describe("getPRNumber", async () => {
   });
 });
 
-const testChangelog = `${EMPTY_CHANGELOG.trimEnd()}
-
-## 4.23.7
-
-- Other change
-
-## 4.23.6
-
-${NO_CHANGES_STR}`;
-
-const expectedChangelog = `# CodeQL Action Changelog
-
-## ${UNRELEASED_PLACEHOLDER}
-
-- Update default CodeQL bundle version to
-
-## 4.23.7
-
-- Other change
-
-## 4.23.6
-
-${NO_CHANGES_STR}`;
-
-describe("updateChangelog", async () => {
-  await it("removes `NO_CHANGES_STR` if present in [UNRELEASED] section", async () => {
-    const result = updateChangelog(EMPTY_CHANGELOG, "");
-    assert.ok(!result.includes(NO_CHANGES_STR));
-  });
-
-  await it("doesn't remove `NO_CHANGES_STR` if present in versioned section", async () => {
-    const result = updateChangelog(
-      EMPTY_CHANGELOG.replace(UNRELEASED_PLACEHOLDER, "1.2.3"),
-      "",
+describe("getChangenote", async () => {
+  await it("returns a note linking to the bundle release and the PR", async () => {
+    assert.equal(
+      getChangenote("1.2.3", testPrUrl),
+      "- Update default CodeQL bundle version to [1.2.3](https://github.com/github/codeql-action/releases/tag/codeql-bundle-v1.2.3). [#42](https://github.com/github/codeql-action/pulls/42)\n",
     );
-    assert.ok(result.includes(NO_CHANGES_STR));
-  });
-
-  await it("throws if there are no sections", async () => {
-    assert.throws(() => {
-      updateChangelog(
-        "# CodeQL Action Changelog",
-        "- Update default CodeQL bundle version to",
-      );
-    });
   });
 
-  await it("adds note at the end of the first section", async () => {
-    const result = updateChangelog(
-      testChangelog,
-      "- Update default CodeQL bundle version to",
-    );
-    assert.deepEqual(result, expectedChangelog);
+  await it("returns valid changenote content", async () => {
+    assert.ok(isValidChangenoteContent(getChangenote("1.2.3", testPrUrl)));
   });
 });
diff --git a/pr-checks/bundle-changelog.ts b/pr-checks/bundle-changelog.ts
index 230b80fb86..8019c70904 100755
--- a/pr-checks/bundle-changelog.ts
+++ b/pr-checks/bundle-changelog.ts
@@ -1,17 +1,13 @@
 #!/usr/bin/env npx tsx
 
 /**
- * Updates the changelog with a change note for an updated CodeQL CLI bundle.
+ * Creates a changenote file for an update to the default CodeQL CLI bundle.
  */
 
 import * as fs from "node:fs";
+import * as path from "node:path";
 
-import {
-  parseChangelog,
-  renderChangelog,
-  UNRELEASED_PLACEHOLDER,
-} from "./changelog";
-import { CHANGELOG_FILE, CLI_BUNDLE_RELEASE_URL_PREFIX } from "./config";
+import { CHANGENOTES_DIR, CLI_BUNDLE_RELEASE_URL_PREFIX } from "./config";
 import { getErrorMessage } from "./util";
 
 export const CLI_VERSION_ENV_VAR = "CLI_VERSION";
@@ -58,42 +54,19 @@ export function getPRNumber(prUrl: string) {
 }
 
 /**
- * Updates `changelog` by adding `changelogNote` to the first section.
+ * Returns the contents of the changenote file for an update to the default
+ * CodeQL CLI bundle.
  *
- * @param contents The existing changelog contents.
- * @param changelogNote The note to add to the first section.
+ * @param cliVersion The CodeQL CLI version of the new default bundle.
+ * @param prUrl The URL of the PR that updates the default bundle.
+ * @throws If the PR number can't be determined from `prUrl`.
  */
-export function updateChangelog(contents: string, changelogNote: string) {
-  // If the "[UNRELEASED]" section starts with "no user facing changes", remove that line.
-  contents = contents.replace(
-    `## ${UNRELEASED_PLACEHOLDER}\n\nNo user facing changes.`,
-    `## ${UNRELEASED_PLACEHOLDER}\n`,
-  );
+export function getChangenote(cliVersion: string, prUrl: string): string {
+  // The GitHub Release for the new bundle version.
+  const bundleReleaseUrl = `${CLI_BUNDLE_RELEASE_URL_PREFIX}${cliVersion}`;
 
-  const changelog = parseChangelog(contents);
-
-  if (changelog.sections.length === 0) {
-    throw new Error("The changelog contains no existing sections.");
-  }
-
-  // Add the changelog note to the bottom of the first section.
-  const firstSection = changelog.sections[0];
-  const lastLine = firstSection.bodyLines.pop();
-
-  if (lastLine !== undefined && lastLine.trim() !== "") {
-    // We expect the last line to be empty. If it isn't for some reason,
-    // add it back.
-    firstSection.bodyLines.push(lastLine);
-  }
-
-  firstSection.bodyLines.push(changelogNote);
-
-  // If the last line is empty as expected, then add it back in after the new note.
-  if (lastLine?.trim() === "") {
-    firstSection.bodyLines.push(lastLine);
-  }
-
-  return renderChangelog(changelog);
+  const prNumber = getPRNumber(prUrl);
+  return `- Update default CodeQL bundle version to [${cliVersion}](${bundleReleaseUrl}). [#${prNumber}](${prUrl})\n`;
 }
 
 function main() {
@@ -101,22 +74,19 @@ function main() {
     const cliVersion = getCLIVersion();
     const prUrl = getPRUrl();
 
-    // The GitHub Release for the new bundle version.
-    const bundleReleaseUrl = `${CLI_BUNDLE_RELEASE_URL_PREFIX}${cliVersion}`;
-
-    // Get the PR number from the PR URL.
-    const prNumber = getPRNumber(prUrl);
-    const changelogNote = `- Update default CodeQL bundle version to [${cliVersion}](${bundleReleaseUrl}). [#${prNumber}](${prUrl})`;
-
-    let changelog = fs.readFileSync(CHANGELOG_FILE, "utf-8");
-
-    changelog = updateChangelog(changelog, changelogNote);
-
-    fs.writeFileSync(CHANGELOG_FILE, changelog);
+    // Include the CLI version in the file name so that changenotes for
+    // different bundle updates don't conflict.
+    const changenotePath = path.join(
+      CHANGENOTES_DIR,
+      `update-bundle-${cliVersion}.md`,
+    );
+    fs.writeFileSync(changenotePath, getChangenote(cliVersion, prUrl));
 
     return 0;
   } catch (err) {
-    console.error(`Failed to bundle changelog: ${getErrorMessage(err)}`);
+    console.error(
+      `Failed to create changenote for bundle update: ${getErrorMessage(err)}`,
+    );
     return -1;
   }
 }