This research aimed to investigate the effect of Kahoot on vocabulary mastery for young English learners. This research utilized the quantitative method with Pre-experimental One Group Pre-Test and Post-Test Design. The instrument used to collect the data was vocabulary test that consisted of 20 items. The data were analyzed using descriptive and inferential statistics. The participants of this study were fourth-grade students of SD Dana Punia Singaraja. The findings proven there was a significant effect on vocabulary mastery for young English learners with a moderate effect of effectiveness. Furthermore, the implementation of Kahoot as gamification in English learning was precise in improving young learners' vocabulary mastery.