Cooperative learning takes place when students work together in small groups to help each other comprehend a subject. This meta-analysis aims to determine the impact of cooperative learning on vocational high school students' mathematics learning results compared to those that pertain to conventional learning. Data from 22 research studies, including the sample size, standard deviation, and mean for both the experimental and control groups and other information, were collected using descriptive analysis. The data analysis technique used meta-analysis on forest plots, with analytical techniques including heterogeneity testing, effect size calculation, summary effect calculation using a random-effects model, and identification of publication bias. The results showed that the effectiveness of cooperative learning was 0.89, which gave a medium effect on the mathematics learning outcomes of vocational high school students. The cooperative learning model also provides a measure of higher effectiveness in grade 11 than grade 10 and learning at a sample size of 1-30 students compared to more than 30 students. The effectiveness of cooperative learning on mathematics learning outcomes in the medium effect category, on the other hand, is dependent on grade level variables and sample size. This meta-analysis research provides information to teachers in Indonesia to implement cooperative learning based on the level and number of students in the class to improve the mathematics learning outcomes of vocational high school students.