diff --git a/optimizely/decision_service.py b/optimizely/decision_service.py
index 28275ef..fcbf131 100644
--- a/optimizely/decision_service.py
+++ b/optimizely/decision_service.py
@@ -457,7 +457,13 @@ def get_variation(
             }
 
         # Check to see if user has a decision available for the given experiment
-        if user_profile_tracker is not None and not ignore_user_profile:
+        # CMAB experiments are excluded from UPS because CMAB's dynamic nature
+        # is incompatible with sticky bucketing (UPS doesn't consider TTL or user attributes).
+        if experiment.cmab:
+            message = f'Skipping user profile service for CMAB experiment "{experiment.key}".'
+            self.logger.info(message)
+            decide_reasons.append(message)
+        elif user_profile_tracker is not None and not ignore_user_profile:
             variation = self.get_stored_variation(project_config, experiment, user_profile_tracker.get_user_profile())
             if variation:
                 message = f'Returning previously activated variation ID "{variation}" of experiment ' \
@@ -529,7 +535,8 @@ def get_variation(
             self.logger.info(message)
             decide_reasons.append(message)
             # Store this new decision and return the variation for the user
-            if user_profile_tracker is not None and not ignore_user_profile:
+            # CMAB experiments are excluded from UPS to preserve dynamic bucketing behavior.
+            if user_profile_tracker is not None and not ignore_user_profile and not experiment.cmab:
                 try:
                     user_profile_tracker.update_user_profile(experiment, variation)
                 except: