diff --git a/.github/workflows/README.md b/.github/workflows/README.md
index adb93b5299858..bb0ccb4ec674e 100644
--- a/.github/workflows/README.md
+++ b/.github/workflows/README.md
@@ -10,10 +10,12 @@
 
 ## Automation
 
-| File                        | Role                                                        |
-| :-------------------------- | :---------------------------------------------------------- |
-| `labeling.yml`              | Automatically apply labels on issues and PRs                |
-| `notify-dco-failure.yml`    | Notify a DCO check failure                                  |
-| `notify-dco-failure.js`     | The main script of the `notify-dco-failure.yml` workflow    |
-| `release-note-category.yml` | Validate a release-note category label is applied on a PR   |
-| `release-note-category.js`  | The main script of the `release-note-category.yml` workflow |
+| File                        | Role                                                           |
+| :-------------------------- | :------------------------------------------------------------- |
+| `autoformat.yml`            | Apply autoformatting when a PR is commented with `autoformat`  |
+| `autoformat.js`             | Define utility functions used in the `autoformat.yml` workflow |
+| `labeling.yml`              | Automatically apply labels on issues and PRs                   |
+| `notify-dco-failure.yml`    | Notify a DCO check failure                                     |
+| `notify-dco-failure.js`     | The main script of the `notify-dco-failure.yml` workflow       |
+| `release-note-category.yml` | Validate a release-note category label is applied on a PR      |
+| `release-note-category.js`  | The main script of the `release-note-category.yml` workflow    |
diff --git a/.github/workflows/autoformat.js b/.github/workflows/autoformat.js
new file mode 100644
index 0000000000000..ca76af3d415fd
--- /dev/null
+++ b/.github/workflows/autoformat.js
@@ -0,0 +1,39 @@
+const createCommitStatus = async (context, github, sha, state) => {
+  const { workflow, runId } = context;
+  const { owner, repo } = context.repo;
+  const target_url = `https://github.com/${owner}/${repo}/actions/runs/${runId}`;
+  await github.repos.createCommitStatus({
+    owner,
+    repo,
+    sha,
+    state,
+    target_url,
+    description: sha,
+    context: workflow,
+  });
+};
+
+const createStatus = async (context, github) => {
+  const { owner, repo } = context.repo;
+  const pull_number = context.issue.number;
+  const pr = await github.pulls.get({ owner, repo, pull_number });
+  const { sha, ref } = pr.data.head;
+  await createCommitStatus(context, github, sha, 'pending');
+  return {
+    repository: `${owner}/${repo}`,
+    pull_number,
+    sha,
+    ref,
+  };
+};
+
+const updateStatus = async (context, github, sha, needs) => {
+  const failed = Object.values(needs).some(({ result }) => result === 'failure');
+  const state = failed ? 'failure' : 'success';
+  await createCommitStatus(context, github, sha, state);
+};
+
+module.exports = {
+  createStatus,
+  updateStatus,
+};
diff --git a/.github/workflows/autoformat.yml b/.github/workflows/autoformat.yml
new file mode 100644
index 0000000000000..a70407c0a1dab
--- /dev/null
+++ b/.github/workflows/autoformat.yml
@@ -0,0 +1,194 @@
+# A workflow to apply autoformatting when a PR is commented with 'autoformat'.
+
+name: Autoformat
+on:
+  issue_comment:
+    types: [created, edited]
+
+defaults:
+  run:
+    shell: bash --noprofile --norc -exo pipefail {0}
+
+jobs:
+  check-comment:
+    runs-on: ubuntu-latest
+    if: ${{ github.event.issue.pull_request && contains(github.event.comment.body, 'autoformat') }}
+    outputs:
+      matched: ${{ steps.check-comment.outputs.result }}
+      repository: ${{ fromJSON(steps.create-status.outputs.result).repository }}
+      ref: ${{ fromJSON(steps.create-status.outputs.result).ref }}
+      sha: ${{ fromJSON(steps.create-status.outputs.result).sha }}
+      pull_number: ${{ fromJSON(steps.create-status.outputs.result).pull_number }}
+    steps:
+      - uses: actions/checkout@v2
+      - name: Check comment
+        id: check-comment
+        uses: actions/github-script@v4
+        with:
+          result-encoding: string
+          script: |
+            return context.payload.comment.body.trim() === 'autoformat';
+      - name: Create status
+        id: create-status
+        if: ${{ steps.check-comment.outputs.result == 'true' }}
+        uses: actions/github-script@v4
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          script: |
+            const autoformat = require('./.github/workflows/autoformat.js');
+            return await autoformat.createStatus(context, github);
+
+  check-diff:
+    runs-on: ubuntu-latest
+    needs: check-comment
+    if: ${{ needs.check-comment.outputs.matched == 'true' }}
+    outputs:
+      py_changed: ${{ steps.check-diff.outputs.py_changed }}
+      ui_changed: ${{ steps.check-diff.outputs.ui_changed }}
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-python@v2
+        with:
+          python-version: '3.6'
+      - run: |
+          pip install requests
+      - name: Check diff
+        id: check-diff
+        run: |
+          repository="${{ needs.check-comment.outputs.repository }}"
+          pull_number="${{ needs.check-comment.outputs.pull_number }}"
+          changed_files="$(python dev/list_changed_files.py --repository $repository --pr-num $pull_number)"
+          py_changed=$([[ -z $(echo "$changed_files" | grep '\.py$') ]] && echo "false" || echo "true")
+          ui_changed=$([[ -z $(echo "$changed_files" | grep '^mlflow/server/js') ]] && echo "false" || echo "true")
+          echo "::set-output name=py_changed::$py_changed"
+          echo "::set-output name=ui_changed::$ui_changed"
+
+  python:
+    # Generate a patch to format python files.
+    runs-on: ubuntu-latest
+    needs: [check-comment, check-diff]
+    if: ${{ needs.check-diff.outputs.py_changed == 'true' }}
+    outputs:
+      has_diff: ${{ steps.check-diff.outputs.has_diff }}
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          repository: ${{ needs.check-comment.outputs.repository }}
+          ref: ${{ needs.check-comment.outputs.ref }}
+      - uses: actions/setup-python@v2
+        with:
+          python-version: '3.6'
+      - name: Install dependencies
+        run: |
+          pip install -r requirements/lint-requirements.txt
+      - name: Run black
+        run: |
+          black .
+      - name: Check diff
+        id: check-diff
+        run: |
+          git diff --output=python.diff
+          has_diff=$([[ -z "$(cat python.diff)" ]] && echo "false" || echo "true")
+          echo "::set-output name=has_diff::$has_diff"
+      - uses: actions/upload-artifact@v2
+        if: ${{ steps.check-diff.outputs.has_diff == 'true' }}
+        with:
+          name: python.${{ github.run_id }}.diff
+          path: python.diff
+          if-no-files-found: error
+          retention-days: 1
+
+  ui:
+    # Generate a patch to format files for MLflow UI.
+    runs-on: ubuntu-latest
+    needs: [check-comment, check-diff]
+    if: ${{ needs.check-diff.outputs.ui_changed == 'true' }}
+    outputs:
+      has_diff: ${{ steps.check-diff.outputs.has_diff }}
+    defaults:
+      run:
+        working-directory: mlflow/server/js
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          repository: ${{ needs.check-comment.outputs.repository }}
+          ref: ${{ needs.check-comment.outputs.ref }}
+      - uses: actions/setup-node@v1
+        with:
+          node-version: 10.x
+      - name: Install dependencies
+        run: |
+          npm i
+      - run: |
+          npm run lint:fix
+      - run: |
+          npm run extract-i18n
+      - name: Check diff
+        id: check-diff
+        run: |
+          git diff --output=ui.diff
+          has_diff=$([[ -z "$(cat ui.diff)" ]] && echo "false" || echo "true")
+          echo "::set-output name=has_diff::$has_diff"
+      - uses: actions/upload-artifact@v2
+        if: ${{ steps.check-diff.outputs.has_diff == 'true' }}
+        with:
+          name: ui.${{ github.run_id }}.diff
+          path: mlflow/server/js/ui.diff
+          if-no-files-found: error
+          retention-days: 1
+
+  apply-patches:
+    # Apply the patches and commit changes to the PR branch.
+    runs-on: ubuntu-latest
+    needs: [check-comment, check-diff, python, ui]
+    if: |
+      always() &&
+      (needs.python.result == 'success' && needs.python.outputs.has_diff == 'true') ||
+      (needs.ui.result == 'success' && needs.ui.outputs.has_diff == 'true')
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          repository: ${{ needs.check-comment.outputs.repository }}
+          ref: ${{ needs.check-comment.outputs.ref }}
+          # As described in the doc below, if we use `secrets.GITHUB_TOKEN`, a commit created by
+          # this workflow will not trigger other workflows:
+          # https://docs.github.com/en/actions/security-guides/automatic-token-authentication#using-the-github_token-in-a-workflow
+          # To make it work, commit changes using the mlflow-automation bot (https://github.com/mlflow-automation).
+          token: ${{ secrets.MLFLOW_AUTOMATION_TOKEN }}
+      - uses: actions/download-artifact@v2
+        if: ${{ needs.python.result == 'success' && needs.python.outputs.has_diff == 'true' }}
+        with:
+          name: python.${{ github.run_id }}.diff
+          path: /tmp/patches
+      - uses: actions/download-artifact@v2
+        if: ${{ needs.ui.result == 'success' && needs.ui.outputs.has_diff == 'true' }}
+        with:
+          name: ui.${{ github.run_id }}.diff
+          path: /tmp/patches
+      - name: Apply patches
+        run: |
+          find /tmp/patches -maxdepth 1 -type f -name '*.diff' | xargs git apply --verbose
+          git diff
+      - name: Commit changes
+        run: |
+          git config --global user.name 'mlflow-automation'
+          git config --global user.email 'mlflow-automation@users.noreply.github.com'
+          run_url="https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}"
+          git commit -sam "Autoformat: $run_url"
+          git push
+
+  update-status:
+    runs-on: ubuntu-latest
+    needs: [check-comment, check-diff, python, ui, apply-patches]
+    if: ${{ always() && needs.check-comment.outputs.matched == 'true' }}
+    steps:
+      - uses: actions/checkout@v2
+      - name: Update status
+        uses: actions/github-script@v4
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          script: |
+            const needs = ${{ toJson(needs) }};
+            const sha = '${{ needs.check-comment.outputs.sha }}'
+            const autoformat = require('./.github/workflows/autoformat.js');
+            await autoformat.updateStatus(context, github, sha, needs);
diff --git a/dev/lint.sh b/dev/lint.sh
index 2e7cc91c7735e..972bffe32f6b3 100755
--- a/dev/lint.sh
+++ b/dev/lint.sh
@@ -10,8 +10,10 @@ echo -e "\n========== black ==========\n"
 black --check .
 
 if [ $? -ne 0 ]; then
-  echo 'Run this command to apply Black formatting:'
-  echo '$ pip install $(cat requirements/lint-requirements.txt | grep "black==") && black .'
+  echo '
+To apply black foramtting, do one of the following:
+- Run `pip install $(cat requirements/lint-requirements.txt | grep "^black==") && black .`
+- Comment `autoformat` on the PR'
 fi
 
 echo -e "\n========== pylint ==========\n"