BACKGROUND: Military personnel frequently face unique psychological challenges due to high-stress environments, which increase the risk of mental health issues like anxiety and depression. Acceptance and commitment therapy (ACT) has shown potential in addressing these issues by enhancing psychological flexibility and resilience. AIM: To systematically evaluate the effectiveness of ACT in improving the mental health of military personnel. Through a scoping review and meta-analysis, we quantitatively assess the impact of ACT on psychological outcomes, guiding future research and clinical practice. METHODS: Relevant literature was searched systematically from database inception to June 30, 2023, across multiple databases, including PubMed, Web of Science, Cochrane Library, and Embase. The Joanna Briggs Institute's (JBI) scoping review guidelines were used as the methodological framework. Meta-analysis was performed using a random-effects model, and publication bias was assessed through Egger's regression test and Begg's funnel plot. RESULTS: Twenty-six studies were included, highlighting the application of ACT in addressing PTSD, chronic pain, anxiety, and depression among military personnel. The meta-analysis of eight studies demonstrated a significant positive effect of ACT on mental health, with a pooled mean difference of -4.99 (95%CI: -6.53 to -3.45). Despite high heterogeneity ( CONCLUSION: This study underscores the potential of ACT as an effective intervention for improving the mental health of military personnel. Future research should focus on large-scale, multi-center RCTs to further validate these findings, particularly within diverse military populations.