This meta-analysis intends to determine the impact of cooperative learning model research findings on the mathematics learning outcomes of Indonesian vocational high school students. Based on moderator variables, such as grade level and student sample size, identify efficacy and publication bias measures. Data from descriptive analysis, which included the mean, standard deviation, and sample size, were collected from 21 research projects based on applying the cooperative learning model in the experimental group and direct learning in the control class. Forest plot analysis was the data analysis method used. The results of the measure of the effectiveness of the cooperative learning model on mathematics learning outcomes in grades 10 and 11 were 0.87 and 0.92, with each effect size category being medium. While the effectiveness of the learning model is measured using a sample size of 1 to 30 students, and more than 30 students were 0.94 and 0.83, respectively, each has a medium effect size category. The results of other analyses show no publication bias. The findings of this study provided teachers with information on how to apply effective cooperative learning models to mathematical learning outcomes in 10th and 11th grade and the efficiency of learning with large class size.