diff --git a/.github/workflows/unassign_bot.js b/.github/workflows/unassign_bot.js
new file mode 100644
index 000000000000..d79ffefb1fe3
--- /dev/null
+++ b/.github/workflows/unassign_bot.js
@@ -0,0 +1,191 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+const LABELS = ["good-first-issue", "good-second-issue"];
+const DAY = 24 * 60 * 60 * 1000;
+const INACTIVITY_PERIOD = 15 * DAY;
+
+/**
+ * Returns whether two GitHub usernames match, ignoring case.
+ *
+ * @param {String} a
+ * @param {String} b
+ */
+const sameUser = (a, b) =>
+  Boolean(a && b && a.toLowerCase() === b.toLowerCase());
+
+module.exports = async ({ github, context }) => {
+  const { owner, repo } = context.repo;
+
+  /**
+   * Retrieves all pages of a GitHub API response.
+   *
+   * @param {Function} method
+   * @param {Object} params
+   */
+  const paginate = (method, params) =>
+    github.paginate(method, { owner, repo, per_page: 100, ...params });
+
+  /**
+   * Posts a comment on the specified issue.
+   *
+   * @param {Number} issue_number
+   * @param {String} body
+   */
+  const comment = (issue_number, body) =>
+    github.rest.issues.createComment({ owner, repo, issue_number, body });
+
+  /**
+   * Removes the user from an issue and explains why they were unassigned.
+   *
+   * @param {Number} issue_number
+   * @param {String} login
+   * @param {String} message
+   */
+  const unassign = async (issue_number, login, message) => {
+    await github.rest.issues.removeAssignees({
+      owner,
+      repo,
+      issue_number,
+      assignees: [login],
+    });
+    await comment(issue_number, message);
+  };
+
+  const processed = new Set();
+  let failures = 0;
+
+  // Process each newcomer label, avoiding duplicate issues.
+  for (const label of LABELS) {
+    const issues = await paginate(github.rest.issues.listForRepo, {
+      state: "open",
+      labels: label,
+    });
+
+    for (const issue of issues) {
+      if (
+        issue.pull_request ||
+        !issue.assignees?.length ||
+        processed.has(issue.number)
+      ) {
+        continue;
+      }
+      processed.add(issue.number);
+
+      // Retrieve the timeline to determine assignments and linked PRs.
+      let events;
+      try {
+        events = await paginate(github.rest.issues.listEventsForTimeline, {
+          issue_number: issue.number,
+        });
+      } catch (error) {
+        failures++;
+        console.error(`Failed to retrieve timeline for #${issue.number}`, error);
+        continue;
+      }
+
+      for (const { login } of issue.assignees) {
+        try {
+          // Use the most recent assignment to start the inactivity period.
+          const assignedAt = Math.max(
+            0,
+            ...events
+              .filter(
+                event =>
+                  event.event === "assigned" &&
+                  sameUser(event.assignee?.login, login)
+              )
+              .map(event => Date.parse(event.created_at))
+              .filter(Number.isFinite)
+          );
+
+          if (!assignedAt) continue;
+
+          // Find the assignee's linked PR. Each contributor is expected
+          // to have at most one linked PR for a particular issue.
+          const linkedPr = events.find(
+            event =>
+              event.event === "cross-referenced" &&
+              event.source?.issue?.pull_request &&
+              sameUser(event.source.issue.user?.login, login)
+          )?.source.issue;
+
+          let lastActivity = assignedAt;
+          let pr;
+
+          if (linkedPr) {
+            const response = await github.rest.pulls.get({
+              owner,
+              repo,
+              pull_number: linkedPr.number,
+            });
+            pr = response.data;
+
+            // Only an open PR authored by the assignee counts as activity.
+            if (
+              pr.state === "open" &&
+              sameUser(pr.user?.login, login)
+            ) {
+              const updatedAt = Date.parse(pr.updated_at);
+              if (Number.isFinite(updatedAt)) {
+                lastActivity = Math.max(lastActivity, updatedAt);
+              }
+            }
+          }
+
+          if (Date.now() - lastActivity < INACTIVITY_PERIOD) continue;
+
+          // Close the linked PR before unassigning the contributor.
+          let closedPrNumber;
+
+          if (
+            pr?.state === "open" &&
+            sameUser(pr.user?.login, login)
+          ) {
+            await github.rest.pulls.update({
+              owner,
+              repo,
+              pull_number: pr.number,
+              state: "closed",
+            });
+
+            closedPrNumber = pr.number;
+          }
+
+          await unassign(
+            issue.number,
+            login,
+            `@${login}, you have been automatically unassigned from this issue ` +
+              `after 15 days without activity. ` +
+              (closedPrNumber
+                ? `Your linked PR #${closedPrNumber} has also been closed. `
+                : "") +
+              `If you are still interested in working on this issue, ` +
+              `please ask a maintainer to reassign it and reopen your PR.`
+          );
+        } catch (error) {
+          failures++;
+          console.error(`Failed to process #${issue.number} for ${login}`, error);
+        }
+      }
+    }
+  }
+
+  if (failures) {
+    throw new Error(`Failed to process ${failures} assignment(s).`);
+  }
+};
diff --git a/.github/workflows/unassign_bot.yml b/.github/workflows/unassign_bot.yml
new file mode 100644
index 000000000000..7eaed26220e5
--- /dev/null
+++ b/.github/workflows/unassign_bot.yml
@@ -0,0 +1,46 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+name: Unassign Inactive Contributors
+
+on:
+  schedule:
+    - cron: "0 10 * * *"
+
+permissions:
+  contents: read
+  issues: write
+  pull-requests: write
+
+jobs:
+  unassign-inactive-contributors:
+    name: Unassign inactive contributors
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    steps:
+      - name: Checkout Arrow
+        uses: actions/checkout@v7
+        with:
+          persist-credentials: false
+          sparse-checkout: .github
+
+      - name: Run unassign bot
+        uses: actions/github-script@v9
+        with:
+          script: |
+            const unassignBot = require("./.github/workflows/unassign_bot.js");
+            await unassignBot({ github, context });
diff --git a/docs/source/developers/guide/step_by_step/finding_issues.rst b/docs/source/developers/guide/step_by_step/finding_issues.rst
index 0284f6e93085..a5d40e1c2aa9 100644
--- a/docs/source/developers/guide/step_by_step/finding_issues.rst
+++ b/docs/source/developers/guide/step_by_step/finding_issues.rst
@@ -61,6 +61,13 @@ GitHub issues.
 The issues labeled as good first issues should take no more than two days or
 a weekend to fix them.
 
+The issues labeled ``good-first-issue`` and ``good-second-issue`` are subject
+to a 15-day inactivity policy. If there is no activity on an assignee's linked
+pull request for 15 days, they will be automatically unassigned and their open
+pull request will be closed. Activity on the pull request resets the inactivity
+period. If no pull request has been opened, the inactivity period starts from
+the most recent assignment.
+
 Another way to find issues is to look for the **"Status: needs champion"**
 label. These are enhancement requests that the community has confirmed are
 still wanted, but that have no current owner. They may be more complex than