Beta-alanine is an important oral supplement for improving athletes’ performance, followed by probable effects on body composition. Current meta-analysis was performed to investigate the role of beta-alanine supplementation on body weight, fat mass, free fat mass, and body fat percentage in adults. Methods: Web of Science, PubMed, Scopus, Cochrane library databases, and EMBASE were searched between January 1990 and May 2021. Randomized controlled trials (RCTs) comparing beta-alanine supplementation with a placebo assessing anthropometric indices were included. Meta‐analysis was performed using the random‐effects model. Publication bias was evaluated using standard methods, and subgroup analysis and meta‐regression were carried out. Results: A total of 875 articles were identified through database searching, of which 12 RCTs with 15 datasets were included in the study. This study showed that beta-alanine supplementation did not have any significant effect on body weight [SMD, 0.08; 95% CI (−0.17, 0.33); P=0.517], fat percentage [SMD, 0.09; 95% CI (−0.18, 0.37); P=0.504], fat mass [SMD, 0.10; 95% CI (−0.29, 0.50); P=0.612], and fat free mass [SMD, 0.16; 95% CI (−0.18, 0.49); P=0.517]. Conclusions: Results showed that beta-alanine supplementation does not change body composition significantly.