With the increasing attention to artificial intelligence (AI) in education, this study aims to examine the overall effectiveness of AI on elementary students’ mathematics achievement using a meta-analysis method. A total of 21 empirical studies with 30 independent samples published between January 2000 and June 2022 were used in the study. The study findings revealed that AI had a small effect size on elementary students’ mathematics achievement. The overall effect of AI was 0.351 under the random-effects model. The effect sizes of eight moderating variables, including three research characteristic variables (research type, research design, and sample size) and five opportunity-to-learn variables (mathematics learning topic, intervention duration, AI type, grade level, and organization), were examined. The findings of the study revealed that mathematics learning topic and grade level variables significantly moderate the effect of AI on mathematics achievement. However, the effects of other moderator variables were found to be not significant. This study also suggested practical and research implications based on the results.