Cooperative learning is a learning model in which students support each other's learning in cooperation with each other. In the cooperative learning model, the education process has many advantages in terms of academic, social, psychological, measurement-evaluation, and economic aspects. In this study, which examines the effect of cooperative learning on students' learning outcomes, 23 first-order meta-analysis studies revealed the effects of cooperative learning model-based teaching on students' learning outcomes between 2010-2021, and 23 effect sizes from these studies were combined with the second-order meta-analysis method. In the study, teaching style, performance types, teaching level, research area, publication quality, publication bias status, report types, and location where the research was conducted were considered moderator variables. As a result of the study, it was determined that the effect of cooperative learning models on student outcomes was moderate. It was also revealed that the levels of cooperative learning outcomes for different domains differ. It has been determined that cooperative learning is also an essential factor in student outcomes. In addition, this study determined that the location of the meta-analysis studies was an important factor in the average effect sizes. Suggestions were made in line with the results of the research.