diff --git a/app/customers/backend/router.py b/app/customers/backend/router.py
index bb19ed8..c68bcf5 100644
--- a/app/customers/backend/router.py
+++ b/app/customers/backend/router.py
@@ -11,6 +11,7 @@ import logging
 
 from app.core.database import execute_query, execute_query_single
 from app.services.cvr_service import get_cvr_service
+from app.services.customer_activity_logger import CustomerActivityLogger
 
 logger = logging.getLogger(__name__)
 
@@ -413,6 +414,9 @@ async def create_customer(customer: CustomerCreate):
         
         logger.info(f"✅ Created customer {customer_id}: {customer.name}")
         
+        # Log activity
+        CustomerActivityLogger.log_created(customer_id, customer.name)
+        
         # Fetch and return created customer
         created = execute_query_single(
             "SELECT * FROM customers WHERE id = %s",
@@ -429,7 +433,7 @@ async def update_customer(customer_id: int, update: CustomerUpdate):
     """Update customer information"""
     # Verify customer exists
     existing = execute_query_single(
-        "SELECT id FROM customers WHERE id = %s",
+        "SELECT id, name FROM customers WHERE id = %s",
         (customer_id,))
     if not existing:
         raise HTTPException(status_code=404, detail="Customer not found")
@@ -439,6 +443,8 @@ async def update_customer(customer_id: int, update: CustomerUpdate):
     params = []
     
     update_dict = update.dict(exclude_unset=True)
+    fields_changed = list(update_dict.keys())
+    
     for field, value in update_dict.items():
         updates.append(f"{field} = %s")
         params.append(value)
@@ -454,6 +460,9 @@ async def update_customer(customer_id: int, update: CustomerUpdate):
         execute_update(query, tuple(params))
         logger.info(f"✅ Updated customer {customer_id}")
         
+        # Log activity
+        CustomerActivityLogger.log_updated(customer_id, existing['name'], fields_changed)
+        
         # Fetch and return updated customer
         updated = execute_query_single(
             "SELECT * FROM customers WHERE id = %s",
diff --git a/app/services/customer_activity_logger.py b/app/services/customer_activity_logger.py
new file mode 100644
index 0000000..2f41601
--- /dev/null
+++ b/app/services/customer_activity_logger.py
@@ -0,0 +1,164 @@
+"""
+Customer Activity Logger
+Helper service for logging all customer-related events
+"""
+
+import logging
+from typing import Optional, Dict, Any
+import json
+from app.core.database import execute_insert
+
+logger = logging.getLogger(__name__)
+
+
+class CustomerActivityLogger:
+    """Centralized customer activity logging"""
+    
+    @staticmethod
+    def log(
+        customer_id: int,
+        activity_type: str,
+        description: str,
+        user_id: Optional[int] = 1,  # Default to system user
+        metadata: Optional[Dict[str, Any]] = None
+    ) -> Optional[int]:
+        """
+        Log a customer activity event
+        
+        Args:
+            customer_id: Customer ID
+            activity_type: Type of activity (customer_updated, contact_added, subscription_changed, etc.)
+            description: Human-readable description
+            user_id: User ID performing action (1 = system)
+            metadata: Additional event data as dict
+            
+        Returns:
+            Activity ID or None on failure
+        """
+        try:
+            # Store metadata as JSON string if provided
+            metadata_str = json.dumps(metadata) if metadata else None
+            
+            activity_id = execute_insert(
+                """INSERT INTO customer_activities 
+                   (customer_id, activity_type, description, user_id, metadata)
+                   VALUES (%s, %s, %s, %s, %s)
+                   RETURNING id""",
+                (customer_id, activity_type, description, user_id, metadata_str)
+            )
+            
+            logger.debug(f"📝 Logged customer activity: {activity_type} for customer {customer_id}")
+            return activity_id
+            
+        except Exception as e:
+            logger.error(f"❌ Failed to log customer activity: {e}")
+            return None
+    
+    # Specific activity types
+    
+    @staticmethod
+    def log_created(customer_id: int, customer_name: str, user_id: Optional[int] = 1):
+        """Log customer creation"""
+        return CustomerActivityLogger.log(
+            customer_id=customer_id,
+            activity_type='customer_created',
+            description=f'Kunde oprettet: {customer_name}',
+            user_id=user_id
+        )
+    
+    @staticmethod
+    def log_updated(customer_id: int, customer_name: str, fields_changed: list, user_id: Optional[int] = 1):
+        """Log customer update"""
+        fields_str = ', '.join(fields_changed)
+        return CustomerActivityLogger.log(
+            customer_id=customer_id,
+            activity_type='customer_updated',
+            description=f'Kunde opdateret: {customer_name} - Ændrede felter: {fields_str}',
+            user_id=user_id,
+            metadata={'fields_changed': fields_changed}
+        )
+    
+    @staticmethod
+    def log_deleted(customer_id: int, customer_name: str, user_id: Optional[int] = 1):
+        """Log customer deletion"""
+        return CustomerActivityLogger.log(
+            customer_id=customer_id,
+            activity_type='customer_deleted',
+            description=f'Kunde slettet: {customer_name}',
+            user_id=user_id
+        )
+    
+    @staticmethod
+    def log_contact_added(customer_id: int, contact_name: str, user_id: Optional[int] = 1):
+        """Log contact added"""
+        return CustomerActivityLogger.log(
+            customer_id=customer_id,
+            activity_type='contact_added',
+            description=f'Kontaktperson tilføjet: {contact_name}',
+            user_id=user_id
+        )
+    
+    @staticmethod
+    def log_contact_updated(customer_id: int, contact_name: str, user_id: Optional[int] = 1):
+        """Log contact updated"""
+        return CustomerActivityLogger.log(
+            customer_id=customer_id,
+            activity_type='contact_updated',
+            description=f'Kontaktperson opdateret: {contact_name}',
+            user_id=user_id
+        )
+    
+    @staticmethod
+    def log_contact_deleted(customer_id: int, contact_name: str, user_id: Optional[int] = 1):
+        """Log contact deleted"""
+        return CustomerActivityLogger.log(
+            customer_id=customer_id,
+            activity_type='contact_deleted',
+            description=f'Kontaktperson slettet: {contact_name}',
+            user_id=user_id
+        )
+    
+    @staticmethod
+    def log_subscription_created(customer_id: int, subscription_name: str, user_id: Optional[int] = 1):
+        """Log subscription created"""
+        return CustomerActivityLogger.log(
+            customer_id=customer_id,
+            activity_type='subscription_created',
+            description=f'Abonnement oprettet: {subscription_name}',
+            user_id=user_id
+        )
+    
+    @staticmethod
+    def log_subscription_updated(customer_id: int, subscription_name: str, user_id: Optional[int] = 1):
+        """Log subscription updated"""
+        return CustomerActivityLogger.log(
+            customer_id=customer_id,
+            activity_type='subscription_updated',
+            description=f'Abonnement opdateret: {subscription_name}',
+            user_id=user_id
+        )
+    
+    @staticmethod
+    def log_subscription_deleted(customer_id: int, subscription_name: str, user_id: Optional[int] = 1):
+        """Log subscription deleted"""
+        return CustomerActivityLogger.log(
+            customer_id=customer_id,
+            activity_type='subscription_deleted',
+            description=f'Abonnement slettet: {subscription_name}',
+            user_id=user_id
+        )
+    
+    @staticmethod
+    def log_sync(customer_id: int, source: str, details: str, user_id: Optional[int] = 1):
+        """Log external sync"""
+        return CustomerActivityLogger.log(
+            customer_id=customer_id,
+            activity_type=f'{source}_sync',
+            description=f'{source} synkronisering: {details}',
+            user_id=user_id,
+            metadata={'source': source}
+        )
+
+
+# Export singleton instance
+customer_activity_logger = CustomerActivityLogger()