Objective <p>Given the rapid development of psychosocial interventions for older adults in China and the significant mental health impacts of the COVID-19 pandemic, it is crucial to evaluate psychosocial interventions' effectiveness in promoting mental health of China's older population. To address this need, a systematic review and meta-analysis were conducted.</p> Methods <p>We conducted a comprehensive search across nine electronic databases and Google Scholar for controlled trial studies published between 2018 and 2023. A meta-analytic approach with random-effects models was employed, and moderator analyses explored variability in effect size estimates.</p> Results <p>Thirty-one studies with 5,941 participants were included. Guided by the WHO's framework, mental health indicators were categorized as positive or negative. Positive indicators reflect better mental health with higher values, while negative indicators show worse mental health. Significant effects were noted for negative (g = -1.21, 95% CI: -1.44, 0.99) and positive (g = 0.68, 95% CI: 0.51, 0.84) mental health indicators, moderating by geographic region, intervention type, setting, and delivery modality.</p> Conclusions <p>Psychosocial services could significantly benefit Chinese older adults' mental health. The moderator and subgroup analysis suggests that the most effective interventions involve mental health professionals and utilize multifaceted approaches. Additionally, the results indicate that intervention duration is an important consideration, as shorter-term programs in Hong Kong exhibited relatively smaller effects.</p>