diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9367fc943cb..e7f7d226178 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -130,6 +130,7 @@ Docs: https://docs.openclaw.ai
 - TTS: Restore 3.28 schema compatibility and fallback observability. (#57953) Thanks @joshavant.
 - Telegram/forum topics: restore reply routing to the active topic and keep ACP `sessions_spawn(..., thread=true, mode="session")` bound to that same topic instead of falling back to root chat or losing follow-up routing. (#56060) Thanks @one27001.
 - Config/SecretRef + Control UI: harden SecretRef redaction round-trip restore, block unsafe raw fallback (force Form mode when raw is unavailable), and preflight submitted-config SecretRefs before config write RPC persistence. (#58044) Thanks @joshavant.
+- Config/Telegram: migrate removed `channels.telegram.groupMentionsOnly` into `channels.telegram.groups["*"].requireMention` on load so legacy configs no longer crash at startup. (#55336) thanks @jameslcowan.
 
 ## 2026.3.28
 
diff --git a/src/config/config.legacy-config-detection.accepts-imessage-dmpolicy.test.ts b/src/config/config.legacy-config-detection.accepts-imessage-dmpolicy.test.ts
index c61f4d334ee..02bfbad507e 100644
--- a/src/config/config.legacy-config-detection.accepts-imessage-dmpolicy.test.ts
+++ b/src/config/config.legacy-config-detection.accepts-imessage-dmpolicy.test.ts
@@ -214,6 +214,25 @@ describe("legacy config detection", () => {
     expect(res.changes).toEqual([]);
     expect(res.config).toBeNull();
   });
+
+  it("flags channels.telegram.groupMentionsOnly as legacy in snapshot", async () => {
+    await withSnapshotForConfig(
+      { channels: { telegram: { groupMentionsOnly: true } } },
+      async (ctx) => {
+        expect(ctx.snapshot.valid).toBe(true);
+        expect(
+          ctx.snapshot.legacyIssues.some(
+            (issue) => issue.path === "channels.telegram.groupMentionsOnly",
+          ),
+        ).toBe(true);
+        const parsed = ctx.parsed as {
+          channels?: { telegram?: { groupMentionsOnly?: boolean } };
+        };
+        expect(parsed.channels?.telegram?.groupMentionsOnly).toBe(true);
+      },
+    );
+  });
+
   it("does not rewrite removed messages.tts.enabled migrations", async () => {
     const res = migrateLegacyConfig({
       messages: { tts: { enabled: true } },
diff --git a/src/config/config.legacy-config-detection.rejects-routing-allowfrom.test.ts b/src/config/config.legacy-config-detection.rejects-routing-allowfrom.test.ts
index 887f8dec131..f9002fc49da 100644
--- a/src/config/config.legacy-config-detection.rejects-routing-allowfrom.test.ts
+++ b/src/config/config.legacy-config-detection.rejects-routing-allowfrom.test.ts
@@ -242,6 +242,17 @@ describe("legacy config detection", () => {
       expect(res.issues[0]?.message).toContain('"telegram"');
     }
   });
+  it("rejects channels.telegram.groupMentionsOnly", async () => {
+    const res = validateConfigObject({
+      channels: { telegram: { groupMentionsOnly: true } },
+    });
+    expect(res.ok).toBe(false);
+    if (!res.ok) {
+      expect(res.issues.some((issue) => issue.path === "channels.telegram.groupMentionsOnly")).toBe(
+        true,
+      );
+    }
+  });
   it("rejects gateway.token", async () => {
     const res = validateConfigObject({
       gateway: { token: "legacy-token" },
diff --git a/src/config/legacy-migrate.test.ts b/src/config/legacy-migrate.test.ts
index 4810ad91dc8..7e039bec875 100644
--- a/src/config/legacy-migrate.test.ts
+++ b/src/config/legacy-migrate.test.ts
@@ -77,6 +77,89 @@ describe("legacy migrate mention routing", () => {
     expect(res.changes).toEqual([]);
     expect(res.config).toBeNull();
   });
+
+  it("moves channels.telegram.groupMentionsOnly into groups.*.requireMention", () => {
+    const res = migrateLegacyConfig({
+      channels: {
+        telegram: {
+          groupMentionsOnly: true,
+        },
+      },
+    });
+
+    expect(res.changes).toContain(
+      'Moved channels.telegram.groupMentionsOnly → channels.telegram.groups."*".requireMention.',
+    );
+    expect(res.config?.channels?.telegram?.groups?.["*"]?.requireMention).toBe(true);
+    expect(
+      (res.config?.channels?.telegram as { groupMentionsOnly?: unknown } | undefined)
+        ?.groupMentionsOnly,
+    ).toBeUndefined();
+  });
+
+  it('keeps explicit channels.telegram.groups."*".requireMention when migrating groupMentionsOnly', () => {
+    const res = migrateLegacyConfig({
+      channels: {
+        telegram: {
+          groupMentionsOnly: true,
+          groups: {
+            "*": {
+              requireMention: false,
+            },
+          },
+        },
+      },
+    });
+
+    expect(res.changes).toContain(
+      'Removed channels.telegram.groupMentionsOnly (channels.telegram.groups."*" already set).',
+    );
+    expect(res.config?.channels?.telegram?.groups?.["*"]?.requireMention).toBe(false);
+    expect(
+      (res.config?.channels?.telegram as { groupMentionsOnly?: unknown } | undefined)
+        ?.groupMentionsOnly,
+    ).toBeUndefined();
+  });
+
+  it("does not overwrite invalid channels.telegram.groups when migrating groupMentionsOnly", () => {
+    const res = migrateLegacyConfig({
+      channels: {
+        telegram: {
+          groupMentionsOnly: true,
+          groups: [],
+        },
+      },
+    });
+
+    expect(res.config).toBeNull();
+    expect(res.changes).toContain(
+      "Skipped channels.telegram.groupMentionsOnly migration because channels.telegram.groups already has an incompatible shape; fix remaining issues manually.",
+    );
+    expect(res.changes).toContain(
+      "Migration applied, but config still invalid; fix remaining issues manually.",
+    );
+  });
+
+  it('does not overwrite invalid channels.telegram.groups."*" when migrating groupMentionsOnly', () => {
+    const res = migrateLegacyConfig({
+      channels: {
+        telegram: {
+          groupMentionsOnly: true,
+          groups: {
+            "*": false,
+          },
+        },
+      },
+    });
+
+    expect(res.config).toBeNull();
+    expect(res.changes).toContain(
+      "Skipped channels.telegram.groupMentionsOnly migration because channels.telegram.groups already has an incompatible shape; fix remaining issues manually.",
+    );
+    expect(res.changes).toContain(
+      "Migration applied, but config still invalid; fix remaining issues manually.",
+    );
+  });
 });
 
 describe("legacy migrate tts provider shape", () => {
diff --git a/src/config/legacy.migrations.runtime.ts b/src/config/legacy.migrations.runtime.ts
index eb8ecdc2485..4cc5b34e1a1 100644
--- a/src/config/legacy.migrations.runtime.ts
+++ b/src/config/legacy.migrations.runtime.ts
@@ -215,12 +215,36 @@ function migrateLegacyTtsConfig(
   }
 }
 
+function resolveCompatibleDefaultGroupEntry(section: Record<string, unknown>): {
+  groups: Record<string, unknown>;
+  entry: Record<string, unknown>;
+} | null {
+  const existingGroups = section.groups;
+  if (existingGroups !== undefined && !getRecord(existingGroups)) {
+    return null;
+  }
+  const groups = getRecord(existingGroups) ?? {};
+  const defaultKey = "*";
+  const existingEntry = groups[defaultKey];
+  if (existingEntry !== undefined && !getRecord(existingEntry)) {
+    return null;
+  }
+  const entry = getRecord(existingEntry) ?? {};
+  return { groups, entry };
+}
+
 const MEMORY_SEARCH_RULE: LegacyConfigRule = {
   path: ["memorySearch"],
   message:
     "top-level memorySearch was moved; use agents.defaults.memorySearch instead (auto-migrated on load).",
 };
 
+const GROUP_MENTIONS_ONLY_RULE: LegacyConfigRule = {
+  path: ["channels", "telegram", "groupMentionsOnly"],
+  message:
+    'channels.telegram.groupMentionsOnly was removed; use channels.telegram.groups."*".requireMention instead (auto-migrated on load).',
+};
+
 const GATEWAY_BIND_RULE: LegacyConfigRule = {
   path: ["gateway", "bind"],
   message:
@@ -307,6 +331,53 @@ export const LEGACY_CONFIG_MIGRATIONS_RUNTIME: LegacyConfigMigrationSpec[] = [
       );
     },
   }),
+  defineLegacyConfigMigration({
+    // v2026.2.23 replaced channels.telegram.groupMentionsOnly with
+    // channels.telegram.groups."*".requireMention. Existing configs crash on
+    // startup because gateway auto-migration only runs for registered legacy
+    // keys, and this removed key previously fell through as an unknown field.
+    id: "channels.telegram.groupMentionsOnly->channels.telegram.groups.*.requireMention",
+    describe:
+      "Move channels.telegram.groupMentionsOnly to channels.telegram.groups.*.requireMention",
+    legacyRules: [GROUP_MENTIONS_ONLY_RULE],
+    apply: (raw, changes) => {
+      const channels = ensureRecord(raw, "channels");
+      const telegram = getRecord(channels.telegram);
+      if (!telegram || telegram.groupMentionsOnly === undefined) {
+        return;
+      }
+
+      const groupMentionsOnly = telegram.groupMentionsOnly;
+      const defaultGroupEntry = resolveCompatibleDefaultGroupEntry(telegram);
+      const defaultKey = "*";
+
+      if (!defaultGroupEntry) {
+        changes.push(
+          "Skipped channels.telegram.groupMentionsOnly migration because channels.telegram.groups already has an incompatible shape; fix remaining issues manually.",
+        );
+        return;
+      }
+
+      const { groups, entry } = defaultGroupEntry;
+
+      if (entry.requireMention === undefined) {
+        entry.requireMention = groupMentionsOnly;
+        groups[defaultKey] = entry;
+        telegram.groups = groups;
+        changes.push(
+          'Moved channels.telegram.groupMentionsOnly → channels.telegram.groups."*".requireMention.',
+        );
+      } else {
+        changes.push(
+          'Removed channels.telegram.groupMentionsOnly (channels.telegram.groups."*" already set).',
+        );
+      }
+
+      delete telegram.groupMentionsOnly;
+      channels.telegram = telegram;
+      raw.channels = channels;
+    },
+  }),
   defineLegacyConfigMigration({
     id: "memorySearch->agents.defaults.memorySearch",
     describe: "Move top-level memorySearch to agents.defaults.memorySearch",