Background <p>The accelerating trend of population aging has increased the prevalence of sarcopenia in older adults, which not only impairs quality of life but also places a heavy medical and economic burden on families and society.</p> Methods <p>This meta-analysis aimed to evaluate the effects of resistance exercise on muscle mass, muscle strength, and physical function in older adults with sarcopenia, and to explore the optimal exercise regimen for this population. Literature was retrieved from Web of Science, PubMed, Cochrane Library, and CNKI, with the retrieval period ranging from database inception to 31 May 2026. Eligible randomized controlled trials (RCTs) focusing on resistance exercise interventions for sarcopenia in older adults were included. A total of 13 RCTs involving 546 participants (282 in the intervention group and 264 in the control group) were finally enrolled. </p> Results <p>Meta-analysis showed that resistance exercise significantly improved handgrip strength, gait speed, appendicular skeletal muscle mass index (ASMI), and five-times sit-to-stand performance in older adults with sarcopenia. The pooled mean differences (MD) were 2.95 kg for handgrip strength, 0.15 m/s for gait speed, 0.25 kg/m² for ASMI, and −1.79 s for the five-times sit-to-stand test (all <i>P</i>&lt;0.0001). Subgroup analysis of gait speed indicated that shorter intervention cycles (≤12 weeks), younger age (≤75 years), and a weekly training frequency of three sessions yielded larger effect sizes with higher heterogeneity; conversely, longer cycles (&gt;12 weeks), older age (&gt;75 years), and non-three-session weekly frequency presented lower heterogeneity. High-heterogeneity subgroups were the main source of overall heterogeneity. </p> Conclusions <p>Resistance exercise exerts significant beneficial effects on handgrip strength, ASMI, gait speed, and physical performance, as assessed by the five-times sit-to-stand test, in older adults with sarcopenia.</p>