Abstract Summary Osteosarcopenic obesity (OSO) is a complex disease commonly seen in the elderly. We found that resistance training may improve bone mineral density, skeletal muscle mass, and body fat percentage in patients with OSO. Therefore, resistance training is beneficial for elderly OSO patients and is worth being promoted. Purpose Investigate effects of resistance training on body composition and physical function in elderly osteosarcopenic obesity (OSO) patients. Methods PubMed, Web of Science, Embase, Cochrane Library, Medline, SinoMed, CNKI, and Wanfang Database were searched from inception until October 13, 2021.Two independent researchers extracted the key information from each eligible study. The methodological quality of included studies was assessed using the Physiotherapy Evidence Database (PEDro) scale. The Cochrane Risk of Bias Tool was used to assess the risk of bias. Grading of Recommendations Assessment Development and Evaluation (GRADE) was used to evaluate the quality of the outcomes. Sensitivity analysis indicated the stability of the results. Statistical analysis was performed using Review Manager 5.3. Results Four randomized controlled studies meeting the inclusion criteria were included, with 182 participants. Twelve weeks of resistance training improved bone mineral density (BMD, mean difference (MD) = 0.01 g/cm², 95% confidence interval (CI): 0.001, 0.02, P = 0.03, I² = 0%), skeletal muscle mass (SMM, MD = 1.19 kg, 95% CI: 0.50, 1.89, P = 0.0007, I² = 0%), Z score, timed chair rise test (TCR), and body fat percentage (BFP, MD = − 1.61%, 95% CI: − 2.94, − 0.28, P = 0.02, I² = 50%) but did not significantly affect skeletal muscle mass index (SMI, MD = 0.20 kg/m², 95% CI: − 0.25, 0.64, P = 0.38, I² = 0%) or gait speed (GS). Conclusions Resistance training is a safe and effective intervention that can improve many parameters, including BFP, SMM, and Z score, among OSO patients and is a good option for elderly individuals to improve their physical fitness.