Realistic Mathematics Education (RME) includes identifying and solving problems. Besides, it is an effort to organize a case, reorganize it according to new ideas, and concretize and rediscover the case to understand it better. This research aims to determine the effect of RME-based teaching against traditional methods, develop a general opinion, and contribute to the literature. In the study, the meta-analysis method was used to synthesize the results of independent experimental studies examining RME's effect on academic achievement. The data set of the research was created in September 2022. Necessary searches were carried out within the ULAKBIM TR Index, YÖK Thesis, ERIC and Web of Science databases. As a result of these searches, 54 studies met the selection criteria to be included in the meta-analysis. The random-effects model was used in the research. As a result of the analysis, the calculated effect sizes were all positive. In the light of this finding, it has been concluded that in all studies, RME-based teaching was more effective than traditional methods on students' academic achievement in mathematics. A moderator analysis was also carried out to determine whether the effect sizes differed statistically significantly according to the variables "publication type, sample size, and educational stage." As a result of the moderator analysis, it was concluded that all moderator variables obtained from the GME-based teaching practices significantly affected the combined effect size.