Introduction This study aimed to evaluate the oncological and prognostic significance of adjuvant chemotherapy (CT) in patients with adult granulosa cell tumors of the ovary (AOGCT). Methods We searched the Chinese National Knowledge Infrastructure, Clinical Trials, Wanfang Database, Web of Science, Cochrane Library, and MEDLINE electronic databases for articles published up to May 2023. Reference lists of the enrolled studies, Google Scholar, and scientific meeting reports were also manually searched. Results We enrolled 5641 patients with AOGCT from 33 eligible studies, including 1674 (29.7%) and 3967 (70.3%) patients in the CT and non-CT groups, respectively. Based on the cumulative results, adjuvant CT did not affect the risk of recurrence or progression (R/P) (odds ratio [OR]: 1.67, 95% confidence interval [CI]: 1.01–2.78, I2 = 63%, P = .05) and 5-year overall survival (OR: .86, 95% CI: .70–1.04, I2 = 0%, P = .12) of patients with AOGCT. However, adjuvant CT might reduce the 5-year disease-free survival (OR: 2.90, 95% CI: 1.19–7.08, I2 = 55%, P = .02). Sub-group analysis revealed that adjuvant CT did not affect the risk of R/P in patients with early-stage AOGCT (OR: .78, 95% CI: .43–1.43, I2 = 2%, P = .43) and advanced or recurrent AOGCT (OR: .78, 95% CI: .43–1.43, I2 = 2%, P = .43). Conclusion This meta-analysis suggests that patients with AOGCT might not benefit from adjuvant CT, even those with advanced or recurrent disease. The results should be interpreted with caution because of the inherent limitations of retrospective studies.