diff --git a/backoffice/.env.example b/backoffice/.env.example
index 7722eba..ba80c15 100644
--- a/backoffice/.env.example
+++ b/backoffice/.env.example
@@ -15,3 +15,8 @@ SMTP_PASSWORD=
 MAIL_FALLBACK_FROM=noreply@mivanchenko.de
 # Base URL the manage-booking link in the confirmation email is built from.
 PUBLIC_BASE_URL=https://onboard.mivanchenko.de
+# Owner Telegram notification (#23). Points at n8n's "Owner notify webhook"
+# node (n8n/booking-sync.json), e.g. https://n8n.mivanchenko.de/webhook/owner-notify.
+# Left blank, sending is skipped (logged, not fatal) -- same convention as
+# SMTP_HOST above.
+OWNER_NOTIFY_WEBHOOK_URL=
diff --git a/backoffice/app/booking_api.py b/backoffice/app/booking_api.py
index edacaf4..81de4af 100644
--- a/backoffice/app/booking_api.py
+++ b/backoffice/app/booking_api.py
@@ -15,6 +15,7 @@ from flask import Blueprint, jsonify, request
 import availability
 import booking_db as bdb
 import booking_mail
+import owner_notify
 
 bp = Blueprint("booking_api", __name__, url_prefix="/api/booking")
 
@@ -161,6 +162,7 @@ def create_booking_row(client_id, resource_id, service_id, start_time,
     # owner manual-entry (#20) included -- calling bdb.create_booking()
     # directly would bypass it.
     booking_mail.send_booking_confirmation(client, booking, token)
+    owner_notify.notify(client, booking, "created")  # #23
     return booking, token
 
 
@@ -174,7 +176,9 @@ def cancel_booking_row(client_id, booking_id):
         raise NotFound()
     if existing["status"] == "cancelled":
         raise AlreadyCancelled()
-    return bdb.update_booking(client_id, booking_id, status="cancelled")
+    updated = bdb.update_booking(client_id, booking_id, status="cancelled")
+    owner_notify.notify(bdb.get_client(client_id), updated, "cancelled")  # #23
+    return updated
 
 
 def reschedule_booking_row(client_id, booking_id, new_start):
@@ -203,10 +207,12 @@ def reschedule_booking_row(client_id, booking_id, new_start):
         raise SlotUnavailable()
 
     try:
-        return bdb.update_booking(client_id, booking_id, start_time=new_start,
-                                   end_time=new_end)
+        updated = bdb.update_booking(client_id, booking_id, start_time=new_start,
+                                      end_time=new_end)
     except bdb.BookingConflict:
         raise SlotTaken() from None
+    owner_notify.notify(client, updated, "rescheduled")  # #23
+    return updated
 
 
 class _BadDuration(ValueError):
diff --git a/backoffice/app/owner_notify.py b/backoffice/app/owner_notify.py
new file mode 100644
index 0000000..0e5b440
--- /dev/null
+++ b/backoffice/app/owner_notify.py
@@ -0,0 +1,79 @@
+"""Owner Telegram notification webhook (#23): fires an internal webhook call
+on booking create/cancel/reschedule, with the same {booking, business_name,
+notify_channel} payload shape n8n/booking-sync.json's "Build booking row"
+step used to hand the Telegram node -- plus an "event" field (that node
+never needed, since it only ever fired for a new EA booking) so the message
+text can say what actually happened instead of always "new booking".
+
+Fire-and-forget over HTTP, mirroring mailer.py's background-thread queue: a
+slow/unreachable webhook must never block or fail a booking mutation.
+"""
+import json
+import os
+import queue
+import threading
+import traceback
+import urllib.request
+
+# Left blank, sending is skipped (logged, not fatal) -- same convention as
+# mailer.py's SMTP_HOST. Channel routing (only "telegram" does anything at
+# launch) lives on the n8n side of this webhook, not here -- see #23.
+NOTIFY_WEBHOOK_URL = os.environ.get("OWNER_NOTIFY_WEBHOOK_URL", "")
+
+_queue = queue.Queue()
+
+
+def _serialize_booking(booking):
+    return {k: (v.isoformat() if hasattr(v, "isoformat") else v)
+            for k, v in booking.items()}
+
+
+def _send_now(payload):
+    if not NOTIFY_WEBHOOK_URL:
+        print(f"[owner_notify] OWNER_NOTIFY_WEBHOOK_URL not configured, "
+              f"skipping notify for booking {payload['booking'].get('booking_id')}",
+              flush=True)
+        return
+    req = urllib.request.Request(
+        NOTIFY_WEBHOOK_URL,
+        data=json.dumps(payload).encode("utf-8"),
+        headers={"Content-Type": "application/json"},
+        method="POST",
+    )
+    with urllib.request.urlopen(req, timeout=10):
+        pass
+
+
+def _worker():
+    while True:
+        payload = _queue.get()
+        try:
+            _send_now(payload)
+        except Exception:  # noqa: BLE001
+            print(f"[owner_notify] send for booking "
+                  f"{payload['booking'].get('booking_id')} failed:", flush=True)
+            traceback.print_exc()
+        finally:
+            _queue.task_done()
+
+
+threading.Thread(target=_worker, daemon=True).start()
+
+
+def notify(client, booking, event):
+    """Queue a best-effort owner notification for a booking create/cancel/
+    reschedule (#23). event is "created"/"cancelled"/"rescheduled" -- booking
+    status alone can't distinguish a fresh booking from a rescheduled one
+    (both land as "confirmed"), and the n8n message text needs to say which
+    happened. Fires for every notify_channel value, including one that isn't
+    "telegram" (or is unset) -- that's not an error, the n8n workflow this
+    webhook feeds is what decides whether a given channel actually sends
+    anything, which keeps this call site the same regardless of how many
+    channels exist in the future."""
+    payload = {
+        "event": event,
+        "booking": _serialize_booking(booking),
+        "business_name": (client or {}).get("business_name") or "",
+        "notify_channel": (client or {}).get("notify_channel"),
+    }
+    _queue.put(payload)
diff --git a/backoffice/app/tests/test_booking_api.py b/backoffice/app/tests/test_booking_api.py
index 4e57366..07b973d 100644
--- a/backoffice/app/tests/test_booking_api.py
+++ b/backoffice/app/tests/test_booking_api.py
@@ -102,6 +102,37 @@ def test_create_booking_via_public_endpoint_sends_confirmation_email(client, mon
     assert "Haircut" in sent[0]["html"]
 
 
+def test_create_booking_notifies_owner(client, monkeypatch):
+    """#23's acceptance criterion: creating a booking via the public API
+    triggers the owner notification webhook, carrying the client's
+    notify_channel and business_name alongside the booking."""
+    notified = []
+    monkeypatch.setattr(
+        "owner_notify.notify",
+        lambda client, booking, event: notified.append((client, booking, event)))
+    resource, service = _setup_resource_and_service(
+        auto_confirm=True, min_notice_minutes=0, max_advance_days=365)
+    day = _next_monday(date.today())
+    slots = client.get("/api/booking/slots", query_string={
+        "client_id": CLIENT_A, "resource_id": resource["resource_id"],
+        "service_id": service["service_id"],
+        "date_from": day.isoformat(), "date_to": day.isoformat()}).get_json()["slots"]
+
+    resp = client.post("/api/booking", json={
+        "client_id": CLIENT_A, "resource_id": resource["resource_id"],
+        "service_id": service["service_id"], "start_time": slots[0],
+        "customer_name": "Nia", "customer_contact": "nia@example.com"})
+    assert resp.status_code == 201
+    booking_id = resp.get_json()["booking_id"]
+
+    assert len(notified) == 1
+    notified_client, notified_booking, notified_event = notified[0]
+    assert notified_client["client_id"] == CLIENT_A
+    assert notified_booking["booking_id"] == booking_id
+    assert notified_booking["customer_name"] == "Nia"
+    assert notified_event == "created"
+
+
 def test_create_booking_auto_confirm_false_yields_pending(client):
     resource, service = _setup_resource_and_service(
         auto_confirm=False, min_notice_minutes=0, max_advance_days=365)
@@ -180,6 +211,64 @@ def test_cancel_with_valid_token_cancels_booking(client):
     assert resp3.status_code == 400
 
 
+def test_cancel_notifies_owner(client, monkeypatch):
+    notified = []
+    monkeypatch.setattr(
+        "owner_notify.notify",
+        lambda client, booking, event: notified.append((client, booking, event)))
+    resource, service = _setup_resource_and_service(
+        min_notice_minutes=0, max_advance_days=365)
+    day = _next_monday(date.today())
+    slot = client.get("/api/booking/slots", query_string={
+        "client_id": CLIENT_A, "resource_id": resource["resource_id"],
+        "service_id": service["service_id"],
+        "date_from": day.isoformat(), "date_to": day.isoformat()}).get_json()["slots"][0]
+    created = client.post("/api/booking", json={
+        "client_id": CLIENT_A, "resource_id": resource["resource_id"],
+        "service_id": service["service_id"], "start_time": slot,
+        "customer_name": "Omar", "customer_contact": "o@example.com"}).get_json()
+    notified.clear()  # drop the create-time notification, isolate the cancel one
+
+    resp = client.post("/api/booking/cancel", json={"token": created["token"]})
+    assert resp.status_code == 200
+
+    assert len(notified) == 1
+    notified_client, notified_booking, notified_event = notified[0]
+    assert notified_client["client_id"] == CLIENT_A
+    assert notified_booking["booking_id"] == created["booking_id"]
+    assert notified_booking["status"] == "cancelled"
+    assert notified_event == "cancelled"
+
+
+def test_reschedule_notifies_owner(client, monkeypatch):
+    notified = []
+    monkeypatch.setattr(
+        "owner_notify.notify",
+        lambda client, booking, event: notified.append((client, booking, event)))
+    resource, service = _setup_resource_and_service(
+        min_notice_minutes=0, max_advance_days=365)
+    day = _next_monday(date.today())
+    slot_list = client.get("/api/booking/slots", query_string={
+        "client_id": CLIENT_A, "resource_id": resource["resource_id"],
+        "service_id": service["service_id"],
+        "date_from": day.isoformat(), "date_to": day.isoformat()}).get_json()["slots"]
+    created = client.post("/api/booking", json={
+        "client_id": CLIENT_A, "resource_id": resource["resource_id"],
+        "service_id": service["service_id"], "start_time": slot_list[0],
+        "customer_name": "Priya", "customer_contact": "p@example.com"}).get_json()
+    notified.clear()  # drop the create-time notification, isolate the reschedule one
+
+    resp = client.post("/api/booking/reschedule", json={
+        "token": created["token"], "start_time": slot_list[2]})
+    assert resp.status_code == 200
+
+    assert len(notified) == 1
+    notified_client, notified_booking, notified_event = notified[0]
+    assert notified_client["client_id"] == CLIENT_A
+    assert notified_booking["start_time"].isoformat() == slot_list[2]
+    assert notified_event == "rescheduled"
+
+
 def test_cancel_with_expired_token_is_rejected(client):
     import jwt as pyjwt
     from booking_api import TOKEN_SECRET
diff --git a/backoffice/app/tests/test_owner_notify.py b/backoffice/app/tests/test_owner_notify.py
new file mode 100644
index 0000000..93ed534
--- /dev/null
+++ b/backoffice/app/tests/test_owner_notify.py
@@ -0,0 +1,88 @@
+"""Unit tests for owner_notify.py's webhook-call shape (#23). Calls
+_send_now directly rather than going through the background-thread queue,
+so assertions are synchronous -- the queue itself is just plumbing.
+"""
+from datetime import datetime, timezone
+
+import pytest
+
+import owner_notify
+
+
+class _FakeResponse:
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *exc):
+        return False
+
+
+def _booking():
+    return {
+        "booking_id": "BK-1",
+        "client_id": "C-1",
+        "customer_name": "Alice",
+        "customer_contact": "alice@example.com",
+        "service": "Haircut",
+        "start_time": datetime(2026, 8, 10, 9, 0, tzinfo=timezone.utc),
+        "end_time": datetime(2026, 8, 10, 10, 0, tzinfo=timezone.utc),
+        "source": "public",
+        "status": "confirmed",
+    }
+
+
+def test_send_now_skips_when_webhook_url_not_configured(monkeypatch):
+    monkeypatch.setattr(owner_notify, "NOTIFY_WEBHOOK_URL", "")
+    calls = []
+    monkeypatch.setattr(owner_notify.urllib.request, "urlopen",
+                         lambda *a, **kw: calls.append((a, kw)) or _FakeResponse())
+    owner_notify._send_now({"booking": _booking(), "business_name": "Happy Nails",
+                             "notify_channel": "telegram"})
+    assert calls == []
+
+
+def test_send_now_posts_json_when_configured(monkeypatch):
+    monkeypatch.setattr(owner_notify, "NOTIFY_WEBHOOK_URL", "https://n8n.example.com/webhook/owner-notify")
+    captured = []
+
+    def fake_urlopen(req, timeout=None):
+        captured.append(req)
+        return _FakeResponse()
+
+    monkeypatch.setattr(owner_notify.urllib.request, "urlopen", fake_urlopen)
+    payload = {"booking": owner_notify._serialize_booking(_booking()),
+               "business_name": "Happy Nails", "notify_channel": "telegram"}
+    owner_notify._send_now(payload)
+    assert len(captured) == 1
+    req = captured[0]
+    assert req.full_url == "https://n8n.example.com/webhook/owner-notify"
+    assert req.get_header("Content-type") == "application/json"
+    import json
+    body = json.loads(req.data)
+    assert body["booking"]["booking_id"] == "BK-1"
+    assert body["booking"]["start_time"] == "2026-08-10T09:00:00+00:00"
+    assert body["business_name"] == "Happy Nails"
+    assert body["notify_channel"] == "telegram"
+
+
+def test_notify_enqueues_regardless_of_channel(monkeypatch):
+    """Channel routing (only "telegram" sends anything real) lives on the
+    n8n side of this webhook, not in notify() -- an unset/other channel is
+    still queued, not silently dropped here (#23)."""
+    captured = []
+    monkeypatch.setattr(owner_notify._queue, "put", lambda p: captured.append(p))
+    client = {"business_name": "Happy Nails", "notify_channel": "email"}
+    owner_notify.notify(client, _booking(), "created")
+    assert len(captured) == 1
+    assert captured[0]["notify_channel"] == "email"
+    assert captured[0]["business_name"] == "Happy Nails"
+    assert captured[0]["event"] == "created"
+
+
+def test_notify_defaults_business_name_and_channel_when_client_missing(monkeypatch):
+    captured = []
+    monkeypatch.setattr(owner_notify._queue, "put", lambda p: captured.append(p))
+    owner_notify.notify(None, _booking(), "cancelled")
+    assert captured[0]["business_name"] == ""
+    assert captured[0]["notify_channel"] is None
+    assert captured[0]["event"] == "cancelled"
diff --git a/backoffice/docker-compose.yml b/backoffice/docker-compose.yml
index f68fd71..36e1368 100644
--- a/backoffice/docker-compose.yml
+++ b/backoffice/docker-compose.yml
@@ -32,6 +32,7 @@ services:
       SMTP_PASSWORD: ${SMTP_PASSWORD}
       MAIL_FALLBACK_FROM: ${MAIL_FALLBACK_FROM}
       PUBLIC_BASE_URL: ${PUBLIC_BASE_URL}
+      OWNER_NOTIFY_WEBHOOK_URL: ${OWNER_NOTIFY_WEBHOOK_URL}
     depends_on:
       smb-db:
         condition: service_healthy
diff --git a/n8n/booking-sync.json b/n8n/booking-sync.json
index 195ba9d..4f97671 100644
--- a/n8n/booking-sync.json
+++ b/n8n/booking-sync.json
@@ -68,7 +68,7 @@
         "resource": "message",
         "operation": "sendMessage",
         "chatId": "5499280257",
-        "text": "=📅 Neue Buchung\nBetrieb: {{ $('Build booking row').item.json.business_name || $('Build booking row').item.json.booking.client_id }}\nKunde: {{ $('Build booking row').item.json.booking.customer_name || '—' }}\nLeistung: {{ $('Build booking row').item.json.booking.service || '—' }}\nWann: {{ $('Build booking row').item.json.booking.start_time || '—' }}\nKontakt: {{ $('Build booking row').item.json.booking.customer_contact || '—' }}\nQuelle: {{ $('Build booking row').item.json.booking.source }}",
+        "text": "=📅 {{ $json.body.event === 'cancelled' ? 'Buchung storniert' : $json.body.event === 'rescheduled' ? 'Buchung verschoben' : 'Neue Buchung' }}\nBetrieb: {{ $json.body.business_name || $json.body.booking.client_id }}\nKunde: {{ $json.body.booking.customer_name || '—' }}\nLeistung: {{ $json.body.booking.service || '—' }}\nWann: {{ $json.body.booking.start_time || '—' }}\nKontakt: {{ $json.body.booking.customer_contact || '—' }}\nQuelle: {{ $json.body.booking.source }}",
         "additionalFields": {
           "appendAttribution": false
         }
@@ -79,7 +79,7 @@
       "typeVersion": 1.2,
       "position": [
         900,
-        300
+        500
       ],
       "credentials": {
         "telegramApi": {
@@ -87,6 +87,57 @@
           "name": "SMB Telegram (leads bot)"
         }
       }
+    },
+    {
+      "parameters": {
+        "httpMethod": "POST",
+        "path": "owner-notify",
+        "responseMode": "onReceived",
+        "options": {
+          "allowedOrigins": "*"
+        }
+      },
+      "id": "b0000000-1111-2222-3333-888888888888",
+      "name": "Owner notify webhook",
+      "type": "n8n-nodes-base.webhook",
+      "typeVersion": 2,
+      "position": [
+        240,
+        500
+      ],
+      "webhookId": "smb-owner-notify-webhook-0001"
+    },
+    {
+      "parameters": {
+        "conditions": {
+          "options": {
+            "caseSensitive": true,
+            "leftValue": "",
+            "typeValidation": "strict"
+          },
+          "conditions": [
+            {
+              "id": "b0000000-1111-2222-3333-aaaaaaaaaaaa",
+              "leftValue": "={{ $json.body.notify_channel }}",
+              "rightValue": "telegram",
+              "operator": {
+                "type": "string",
+                "operation": "equals"
+              }
+            }
+          ],
+          "combinator": "and"
+        },
+        "options": {}
+      },
+      "id": "b0000000-1111-2222-3333-999999999999",
+      "name": "Telegram channel?",
+      "type": "n8n-nodes-base.if",
+      "typeVersion": 2,
+      "position": [
+        460,
+        500
+      ]
     }
   ],
   "connections": {
@@ -112,7 +163,18 @@
         ]
       ]
     },
-    "Save to CRM (bookings)": {
+    "Owner notify webhook": {
+      "main": [
+        [
+          {
+            "node": "Telegram channel?",
+            "type": "main",
+            "index": 0
+          }
+        ]
+      ]
+    },
+    "Telegram channel?": {
       "main": [
         [
           {