diff --git a/lib/optimizely/decision_service.rb b/lib/optimizely/decision_service.rb
index 051a8b6..23db175 100644
--- a/lib/optimizely/decision_service.rb
+++ b/lib/optimizely/decision_service.rb
@@ -100,7 +100,9 @@ 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
-      unless should_ignore_user_profile_service && user_profile_tracker
+      # Skip UPS for CMAB experiments as they require dynamic decisions
+      is_cmab_experiment = experiment.key?('cmab')
+      unless should_ignore_user_profile_service || is_cmab_experiment || !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
@@ -111,6 +113,13 @@ def get_variation(project_config, experiment_id, user_context, user_profile_trac
         end
       end
 
+      # Add decision reason when UPS is skipped for CMAB
+      if is_cmab_experiment && !should_ignore_user_profile_service && user_profile_tracker
+        message = 'User Profile Service is not used for CMAB experiments.'
+        @logger.log(Logger::INFO, message)
+        decide_reasons.push(message)
+      end
+
       # Check audience conditions
       user_meets_audience_conditions, reasons_received = Audience.user_meets_audience_conditions?(project_config, experiment, user_context, @logger)
       decide_reasons.push(*reasons_received)
@@ -155,7 +164,8 @@ 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
+      # Skip UPS for CMAB experiments as they require dynamic decisions
+      user_profile_tracker.update_user_profile(experiment_id, variation_id) unless should_ignore_user_profile_service || is_cmab_experiment || !user_profile_tracker
       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..610c23c 100644
--- a/spec/decision_service_spec.rb
+++ b/spec/decision_service_spec.rb
@@ -1166,5 +1166,74 @@
         expect(spy_cmab_service).not_to have_received(:get_decision)
       end
     end
+
+    describe 'when user profile service is enabled' do
+      it 'should skip user profile service lookup and save for CMAB experiments' do
+        # Create a CMAB experiment configuration
+        cmab_experiment = {
+          'id' => '111150',
+          'key' => 'cmab_experiment',
+          'status' => 'Running',
+          'layerId' => '111150',
+          'audienceIds' => [],
+          'forcedVariations' => {},
+          'variations' => [
+            {'id' => '111151', 'key' => 'variation_1'},
+            {'id' => '111152', 'key' => 'variation_2'}
+          ],
+          'trafficAllocation' => [
+            {'entityId' => '111151', 'endOfRange' => 5000},
+            {'entityId' => '111152', 'endOfRange' => 10_000}
+          ],
+          'cmab' => {'trafficAllocation' => 5000}
+        }
+        user_context = project_instance.create_user_context('test_user', {})
+
+        # Create user profile tracker
+        user_profile_service = Optimizely::UserProfileService.new
+        user_profile_tracker = Optimizely::UserProfileTracker.new('test_user', user_profile_service, spy_logger)
+
+        # Mock experiment lookup to return our CMAB experiment
+        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)
+
+        # Mock audience evaluation to pass
+        allow(Optimizely::Audience).to receive(:user_meets_audience_conditions?).and_return([true, []])
+
+        # Mock bucketer to return a valid entity ID (user is in traffic allocation)
+        allow(decision_service.bucketer).to receive(:bucket_to_entity_id)
+          .with(config, cmab_experiment, 'test_user', 'test_user')
+          .and_return(['$', []])
+
+        # Mock CMAB service to return a decision
+        allow(spy_cmab_service).to receive(:get_decision)
+          .with(config, user_context, '111150', [])
+          .and_return(Optimizely::CmabDecision.new(variation_id: '111151', cmab_uuid: 'test-cmab-uuid-123'))
+
+        # Mock variation lookup
+        allow(config).to receive(:get_variation_from_id_by_experiment_id)
+          .with('111150', '111151')
+          .and_return({'id' => '111151', 'key' => 'variation_1'})
+
+        # Spy on user profile tracker methods
+        allow(user_profile_tracker).to receive(:update_user_profile).and_call_original
+        allow(decision_service).to receive(:get_saved_variation_id).and_call_original
+
+        variation_result = decision_service.get_variation(config, '111150', user_context, user_profile_tracker)
+
+        expect(variation_result.variation_id).to eq('111151')
+        expect(variation_result.cmab_uuid).to eq('test-cmab-uuid-123')
+        expect(variation_result.error).to eq(false)
+
+        # Verify UPS lookup was NOT called for CMAB
+        expect(decision_service).not_to have_received(:get_saved_variation_id)
+
+        # Verify UPS save was NOT called for CMAB
+        expect(user_profile_tracker).not_to have_received(:update_user_profile)
+
+        # Verify the UPS exclusion message is in reasons
+        expect(variation_result.reasons).to include('User Profile Service is not used for CMAB experiments.')
+      end
+    end
   end
 end