A meta-analysis of 187 studies containing 247 independent studies (N = 68,429) on gender differences in academic self-efficacy identified an overall effect size of 0.08, with a small difference favoring males. Moderator analysis demonstrated that content domain was a significant moderator in explaining effect size variation. Females displayed higher language arts self-efficacy than males. Meanwhile, males exhibited higher mathematics, computer, and social sciences self-efficacy than females. Gender differences in academic self-efficacy also varied with age. The largest effect size occurred for respondents aged over 23 years old. For mathematics self-efficacy, the significant gender differences emerged in late adolescence. Future research should longitudinally examine gender differences in academic self-efficacy to determine the prevalence of gender differences during different life stages.