diff --git a/lib/optimizely/decision_service.rb b/lib/optimizely/decision_service.rb
index 051a8b6..32ac106 100644
--- a/lib/optimizely/decision_service.rb
+++ b/lib/optimizely/decision_service.rb
@@ -100,14 +100,22 @@ def get_variation(project_config, experiment_id, user_context, user_profile_trac
 
       should_ignore_user_profile_service = decide_options.include? Optimizely::Decide::OptimizelyDecideOption::IGNORE_USER_PROFILE_SERVICE
       # Check for saved bucketing decisions if decide_options do not include ignoreUserProfileService
+      # CMAB experiments are excluded from UserProfileService to allow dynamic decisions
+      is_cmab_experiment = experiment.key?('cmab')
       unless should_ignore_user_profile_service && user_profile_tracker
-        saved_variation_id, reasons_received = get_saved_variation_id(project_config, experiment_id, user_profile_tracker.user_profile)
-        decide_reasons.push(*reasons_received)
-        if saved_variation_id
-          message = "Returning previously activated variation ID #{saved_variation_id} of experiment '#{experiment_key}' for user '#{user_id}' from user profile."
+        unless is_cmab_experiment
+          saved_variation_id, reasons_received = get_saved_variation_id(project_config, experiment_id, user_profile_tracker.user_profile)
+          decide_reasons.push(*reasons_received)
+          if saved_variation_id
+            message = "Returning previously activated variation ID #{saved_variation_id} of experiment '#{experiment_key}' for user '#{user_id}' from user profile."
+            @logger.log(Logger::INFO, message)
+            decide_reasons.push(message)
+            return VariationResult.new(nil, false, decide_reasons, saved_variation_id)
+          end
+        else
+          message = 'User profile service excluded for CMAB experiment to allow dynamic decisions.'
           @logger.log(Logger::INFO, message)
           decide_reasons.push(message)
-          return VariationResult.new(nil, false, decide_reasons, saved_variation_id)
         end
       end
 
@@ -155,7 +163,8 @@ def get_variation(project_config, experiment_id, user_context, user_profile_trac
       decide_reasons.push(message) if message
 
       # Persist bucketing decision
-      user_profile_tracker.update_user_profile(experiment_id, variation_id) unless should_ignore_user_profile_service && user_profile_tracker
+      # CMAB experiments are excluded from UserProfileService
+      user_profile_tracker.update_user_profile(experiment_id, variation_id) unless should_ignore_user_profile_service && user_profile_tracker || is_cmab_experiment
       VariationResult.new(cmab_uuid, false, decide_reasons, variation_id)
     end
 
diff --git a/spec/decision_service_spec.rb b/spec/decision_service_spec.rb
index 30ad7d2..6080ef4 100644
--- a/spec/decision_service_spec.rb
+++ b/spec/decision_service_spec.rb
@@ -1166,5 +1166,68 @@
         expect(spy_cmab_service).not_to have_received(:get_decision)
       end
     end
+
+    describe 'UserProfileService exclusion for CMAB' do
+      it 'should exclude CMAB experiments from UserProfileService and include decision reason' do
+        # Create a CMAB experiment
+        cmab_experiment = {
+          'id' => '111150',
+          'key' => 'cmab_experiment',
+          'status' => 'Running',
+          'audienceIds' => [],
+          'audienceConditions' => [],
+          'forcedVariations' => {},
+          'layerId' => '1',
+          'trafficAllocation' => [
+            {'entityId' => '111151', 'endOfRange' => 10_000}
+          ],
+          'variations' => [
+            {'id' => '111151', 'key' => 'variation_1', 'variables' => []}
+          ],
+          'cmab' => true
+        }
+
+        # Setup mocks for CMAB decision
+        cmab_decision = Optimizely::CmabService::CmabDecision.new('111151', 'test-uuid')
+        allow(spy_cmab_service).to receive(:get_decision)
+          .and_return([cmab_decision, ['CMAB decision made']])
+
+        # Setup user profile service with a stored variation
+        stored_profile = {
+          'user_id' => 'test_user',
+          'experiment_bucket_map' => {
+            '111150' => {'variation_id' => '111152'}  # Different variation
+          }
+        }
+        allow(spy_user_profile_service).to receive(:lookup).and_return(stored_profile)
+
+        # Setup config mocks
+        allow(config).to receive(:get_experiment_from_id).with('111150').and_return(cmab_experiment)
+        allow(config).to receive(:experiment_running?).with(cmab_experiment).and_return(true)
+        allow(config).to receive(:get_variation_from_id_by_experiment_id)
+          .with('111150', '111151')
+          .and_return({'id' => '111151', 'key' => 'variation_1'})
+
+        # Create user profile tracker
+        user_profile_tracker = Optimizely::UserProfileTracker.new('test_user', spy_user_profile_service, spy_logger)
+
+        # Call get_variation
+        user_context = project_instance.create_user_context('test_user')
+        variation_result = decision_service.get_variation(config, '111150', user_context, user_profile_tracker)
+
+        # Verify the CMAB decision was used (variation_1), not the stored profile (111152)
+        expect(variation_result.variation_id).to eq('111151')
+        expect(variation_result.cmab_uuid).to eq('test-uuid')
+
+        # Verify the UPS exclusion reason is in the decision reasons
+        expect(variation_result.reasons).to include('User profile service excluded for CMAB experiment to allow dynamic decisions.')
+
+        # Verify UPS lookup was NOT called (bypassed)
+        expect(spy_user_profile_service).not_to have_received(:lookup)
+
+        # Verify UPS save was NOT called (bypassed)
+        expect(spy_user_profile_service).not_to have_received(:save)
+      end
+    end
   end
 end