diff --git a/.github/workflows/pr-review-reminder.yml b/.github/workflows/pr-review-reminder.yml
new file mode 100644
index 000000000000..3eda72221948
--- /dev/null
+++ b/.github/workflows/pr-review-reminder.yml
@@ -0,0 +1,39 @@
+name: 'PR: Review Reminder'
+
+on:
+  workflow_dispatch:
+  schedule:
+    # Run on weekdays at 10:00 AM UTC. No new reminders can fire on weekends because
+    # Saturday/Sunday are never counted as business days.
+    - cron: '0 10 * * 1-5'
+
+# pulls.* list + listRequestedReviewers → pull-requests: read
+# issues timeline + comments + createComment → issues: write
+# repos.listCollaborators (outside) → Metadata read on the token (see GitHub App permission map)
+# checkout → contents: read
+permissions:
+  contents: read
+  issues: write
+  pull-requests: read
+
+concurrency:
+  group: ${{ github.workflow }}
+  cancel-in-progress: false
+
+jobs:
+  remind-reviewers:
+    # `schedule` has no `repository` on github.event; forks must be skipped only for workflow_dispatch.
+    if: github.event_name == 'schedule' || github.event.repository.fork != true
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Remind pending reviewers
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const { default: run } = await import(
+              `${process.env.GITHUB_WORKSPACE}/scripts/pr-review-reminder.mjs`
+            );
+            await run({ github, context, core });
diff --git a/scripts/pr-review-reminder.mjs b/scripts/pr-review-reminder.mjs
new file mode 100644
index 000000000000..5e264e236598
--- /dev/null
+++ b/scripts/pr-review-reminder.mjs
@@ -0,0 +1,290 @@
+/**
+ * PR Review Reminder script.
+ *
+ * Posts reminder comments on open PRs whose requested reviewers have not
+ * responded within 2 business days. Re-nags every 2 business days thereafter
+ * until the review is submitted (or the request is removed).
+ *
+ * @mentions are narrowed as follows:
+ * - Individual users: not [outside collaborators](https://docs.github.com/en/organizations/managing-outside-collaborators)
+ *   on this repo (via `repos.listCollaborators` with `affiliation: outside` — repo-scoped, no extra token).
+ * - Team reviewers: only the org team `team-javascript-sdks` (by slug).
+ *
+ * Business days exclude weekends and public holidays for US, CA, and AT
+ * (fetched at runtime from the Nager.Date API).
+ *
+ * Intended to be called from a GitHub Actions workflow via actions/github-script:
+ *
+ *   const { default: run } = await import(
+ *     `${process.env.GITHUB_WORKSPACE}/scripts/pr-review-reminder.mjs`
+ *   );
+ *   await run({ github, context, core });
+ */
+
+// Team @mentions only for this slug. Individuals are filtered using outside-collaborator list (see below).
+const SDK_TEAM_SLUG = 'team-javascript-sdks';
+
+// ---------------------------------------------------------------------------
+// Outside collaborators (repo API — works with default GITHUB_TOKEN).
+// Org members with access via teams or default permissions are not listed here.
+// ---------------------------------------------------------------------------
+
+async function loadOutsideCollaboratorLogins(github, owner, repo, core) {
+  try {
+    const users = await github.paginate(github.rest.repos.listCollaborators, {
+      owner,
+      repo,
+      affiliation: 'outside',
+      per_page: 100,
+    });
+    return new Set(users.map(u => u.login));
+  } catch (e) {
+    const status = e.response?.status;
+    core.warning(
+      `Could not list outside collaborators for ${owner}/${repo} (${status ? `HTTP ${status}` : 'no status'}): ${e.message}. ` +
+        'Skipping @mentions for individual reviewers (team reminders unchanged).',
+    );
+    return null;
+  }
+}
+
+// ---------------------------------------------------------------------------
+// Public holidays (US, Canada, Austria) via Nager.Date — free, no API key.
+// See https://date.nager.at/ for documentation and supported countries.
+// We fetch the current year and the previous year so that reviews requested
+// in late December are handled correctly when the workflow runs in January.
+// If the API is unreachable we fall back to weekday-only checking and warn.
+// ---------------------------------------------------------------------------
+
+const COUNTRY_CODES = ['US', 'CA', 'AT'];
+
+async function fetchHolidaysForYear(year, core) {
+  const dates = new Set();
+  for (const cc of COUNTRY_CODES) {
+    try {
+      const resp = await fetch(`https://date.nager.at/api/v3/PublicHolidays/${year}/${cc}`);
+      if (!resp.ok) {
+        core.warning(`Nager.Date returned ${resp.status} for ${cc}/${year}`);
+        continue;
+      }
+      const holidays = await resp.json();
+      for (const h of holidays) {
+        dates.add(h.date); // 'YYYY-MM-DD'
+      }
+    } catch (e) {
+      core.warning(`Failed to fetch holidays for ${cc}/${year}: ${e.message}`);
+    }
+  }
+  return dates;
+}
+
+// ---------------------------------------------------------------------------
+// Business-day counter.
+// Counts fully-elapsed business days (Mon–Fri, not a public holiday) between
+// requestedAt and now. "Fully elapsed" means the day has completely passed,
+// so today is not included — giving the reviewer the rest of today to respond.
+//
+// Example: review requested Friday → elapsed complete days include Sat, Sun,
+// Mon, Tue, … The first two business days are Mon and Tue, so the reminder
+// fires on Wednesday morning. That gives the reviewer all of Monday and
+// Tuesday to respond.
+// ---------------------------------------------------------------------------
+
+function countElapsedBusinessDays(requestedAt, now, publicHolidays) {
+  // Walk from the day after the request up to (but not including) today.
+  const start = new Date(requestedAt);
+  start.setUTCHours(0, 0, 0, 0);
+  start.setUTCDate(start.getUTCDate() + 1);
+
+  const todayUTC = new Date(now);
+  todayUTC.setUTCHours(0, 0, 0, 0);
+
+  let count = 0;
+  const cursor = new Date(start);
+  while (cursor < todayUTC) {
+    const dow = cursor.getUTCDay(); // 0 = Sun, 6 = Sat
+    if (dow !== 0 && dow !== 6) {
+      const dateStr = cursor.toISOString().slice(0, 10);
+      if (!publicHolidays.has(dateStr)) {
+        count++;
+      }
+    }
+    cursor.setUTCDate(cursor.getUTCDate() + 1);
+  }
+  return count;
+}
+
+// ---------------------------------------------------------------------------
+// Reminder marker helpers
+// ---------------------------------------------------------------------------
+
+// Returns a unique HTML comment marker for a reviewer key (login or "team:slug").
+// Used for precise per-reviewer deduplication in existing comments.
+function reminderMarker(key) {
+  return `<!-- review-reminder:${key} -->`;
+}
+
+// ---------------------------------------------------------------------------
+// Main entry point
+// ---------------------------------------------------------------------------
+
+export default async function run({ github, context, core }) {
+  const { owner, repo } = context.repo;
+  const now = new Date();
+
+  // Fetch public holidays
+  const currentYear = now.getUTCFullYear();
+  const [currentYearHolidays, previousYearHolidays] = await Promise.all([
+    fetchHolidaysForYear(currentYear, core),
+    fetchHolidaysForYear(currentYear - 1, core),
+  ]);
+  const publicHolidays = new Set([...currentYearHolidays, ...previousYearHolidays]);
+
+  core.info(`Loaded ${publicHolidays.size} public holiday dates for ${currentYear - 1}–${currentYear}`);
+
+  const outsideCollaboratorLogins = await loadOutsideCollaboratorLogins(github, owner, repo, core);
+  if (outsideCollaboratorLogins) {
+    core.info(`Excluding ${outsideCollaboratorLogins.size} outside collaborator login(s) from individual @mentions`);
+  }
+
+  // ---------------------------------------------------------------------------
+  // Main loop
+  // ---------------------------------------------------------------------------
+
+  // Fetch all open PRs
+  const prs = await github.paginate(github.rest.pulls.list, {
+    owner,
+    repo,
+    state: 'open',
+    per_page: 100,
+  });
+
+  core.info(`Found ${prs.length} open PRs`);
+
+  for (const pr of prs) {
+    // Skip draft PRs and PRs opened by bots
+    if (pr.draft) continue;
+    if (pr.user?.type === 'Bot') continue;
+
+    // Get currently requested reviewers (only those who haven't reviewed yet —
+    // GitHub automatically removes a reviewer from this list once they submit a review)
+    const { data: requested } = await github.rest.pulls.listRequestedReviewers({
+      owner,
+      repo,
+      pull_number: pr.number,
+    });
+
+    const pendingReviewers = requested.users; // individual users
+    const pendingTeams = requested.teams; // team reviewers
+    if (pendingReviewers.length === 0 && pendingTeams.length === 0) continue;
+
+    // Fetch the PR timeline to determine when each review was (last) requested
+    const timeline = await github.paginate(github.rest.issues.listEventsForTimeline, {
+      owner,
+      repo,
+      issue_number: pr.number,
+      per_page: 100,
+    });
+
+    // Fetch existing comments so we can detect previous reminders
+    const comments = await github.paginate(github.rest.issues.listComments, {
+      owner,
+      repo,
+      issue_number: pr.number,
+      per_page: 100,
+    });
+
+    const botComments = comments.filter(c => c.user?.login === 'github-actions[bot]');
+
+    // Returns the date of the most recent reminder comment that contains the given marker,
+    // or null if no such comment exists.
+    function latestReminderDate(key) {
+      const marker = reminderMarker(key);
+      const matches = botComments
+        .filter(c => c.body.includes(marker))
+        .sort((a, b) => new Date(b.created_at) - new Date(a.created_at));
+      return matches.length > 0 ? new Date(matches[0].created_at) : null;
+    }
+
+    // Returns true if a reminder is due for a reviewer/team:
+    // - The "anchor" is the later of: the review-request date, or the last
+    //   reminder we already posted for this reviewer. This means the
+    //   2-business-day clock restarts after every reminder (re-nagging), and
+    //   also resets when a new push re-requests the review.
+    // - A reminder fires when ≥ 2 full business days have elapsed since the anchor.
+    function needsReminder(requestedAt, key) {
+      const lastReminded = latestReminderDate(key);
+      const anchor = lastReminded && lastReminded > requestedAt ? lastReminded : requestedAt;
+      return countElapsedBusinessDays(anchor, now, publicHolidays) >= 2;
+    }
+
+    // Collect overdue individual reviewers
+    const toRemind = []; // { key, mention }
+
+    for (const reviewer of pendingReviewers) {
+      const requestEvents = timeline
+        .filter(e => e.event === 'review_requested' && e.requested_reviewer?.login === reviewer.login)
+        .sort((a, b) => new Date(b.created_at) - new Date(a.created_at));
+
+      if (requestEvents.length === 0) {
+        core.warning(
+          `PR #${pr.number}: pending reviewer @${reviewer.login} has no matching review_requested timeline event; skipping reminder for them.`,
+        );
+        continue;
+      }
+
+      const requestedAt = new Date(requestEvents[0].created_at);
+      if (!needsReminder(requestedAt, reviewer.login)) continue;
+
+      if (outsideCollaboratorLogins === null) {
+        continue;
+      }
+      if (outsideCollaboratorLogins.has(reviewer.login)) {
+        continue;
+      }
+
+      toRemind.push({ key: reviewer.login, mention: `@${reviewer.login}` });
+    }
+
+    // Collect overdue team reviewers
+    for (const team of pendingTeams) {
+      if (team.slug !== SDK_TEAM_SLUG) {
+        continue;
+      }
+
+      const requestEvents = timeline
+        .filter(e => e.event === 'review_requested' && e.requested_team?.slug === team.slug)
+        .sort((a, b) => new Date(b.created_at) - new Date(a.created_at));
+
+      if (requestEvents.length === 0) {
+        core.warning(
+          `PR #${pr.number}: pending team reviewer @${owner}/${team.slug} has no matching review_requested timeline event; skipping reminder for them.`,
+        );
+        continue;
+      }
+
+      const requestedAt = new Date(requestEvents[0].created_at);
+      const key = `team:${team.slug}`;
+      if (!needsReminder(requestedAt, key)) continue;
+
+      toRemind.push({ key, mention: `@${owner}/${team.slug}` });
+    }
+
+    if (toRemind.length === 0) continue;
+
+    // Build a single comment that includes per-reviewer markers (for precise dedup
+    // on subsequent runs) and @-mentions all overdue reviewers/teams.
+    const markers = toRemind.map(({ key }) => reminderMarker(key)).join('\n');
+    const mentions = toRemind.map(({ mention }) => mention).join(', ');
+    const body = `${markers}\n👋 ${mentions} — Please review this PR when you get a chance!`;
+
+    await github.rest.issues.createComment({
+      owner,
+      repo,
+      issue_number: pr.number,
+      body,
+    });
+
+    core.info(`Posted review reminder on PR #${pr.number} for: ${mentions}`);
+  }
+}