Implementation intentions (II) have demonstrated their efficacy in promoting physical activity (PA) among various populations, including adults, the general population, and those with chronic conditions. However, there is a dearth of meta-analyses examining this efficacy among university students. This meta-analysis aims to determine the effectiveness of II interventions in improving PA among university students. Six online databases (PubMed, Embase, Web of Science, Cochrane Central, PsycINFO, and PsycArticle) were comprehensively searched. Recursive searching and grey literature collection strategies were employed to identify relevant studies. The meta-analysis employed a random-effects model to combine effect sizes for different PA outcomes. The Cochrane Risk of Bias tool was used to assess the quality of the included studies, and sensitivity analysis was performed to assess the robustness of the results. Twelve studies involving 1916 participants met the inclusion criteria. The findings indicated that II interventions significantly increased PA among university students compared to control groups (standardized mean difference [SMD] = 0.31, 95% confidence interval [CI]: 0.12, 0.50, p < 0.001). Subgroup analyses revealed larger effect sizes in the following groups: publication year after 2013, inactive university students, the reinforcement group, the action planning group, and the intervention period of fewer than six weeks. The above findings offer compelling evidence that II interventions can effectively promote PA among university students. The integration of IIs with e-health platforms and the implementation of individualized and multifaceted intervention models exhibit promising sustainability for promoting PA on campus.