Kahoot!-based serious games have received international attention and obtained more than two billion players across over 200 countries and areas (Kahoot!, 2021). However, scanty studies have systematically examined their effect on educational outcomes using a meta-analysis. Through a meta-analysis using Stata/MP 14.0, this study concludes that Kahoot!-based serious games could significantly improve academic achievements and student performance, that the educational level of participants could not predict Kahoot!-assisted academic achievements and student performance, and that the difference in countries or areas could not predict Kahoot!-assisted academic achievements and student performance. More components such as cognitive loads, satisfaction, or anxiety in Kahoot!-based serious games could also be meta-analytically reviewed in the future.