Objective To systematically evaluate the effect of acceptance and commitment therapy (ACT) on the mental health and quality of life of cancer patients. Methods Randomized clinical trials (RCTs) reporting the influence of ACT on mental health and quality of life in cancer patients were searched in the CBM, WanFang, CNKI, VIP, PubMed, Cochrane Library, Web of Science and EMbase databases, and the retrieval time was from the time of building the database to November 2022. Literature screening based on inclusion and exclusion criteria, quality assessment and data extraction were performed by two investigators. A meta-analysis was conducted using Revman5.4 software. Results A total of 14 RCTs representing 1,063 cancer patients were enrolled. Meta-analysis results showed that ACT significantly improved anxiety (SMD=-1.04, 95%CI [-1.19, -0.89], P<0.01), depression (SMD=-0.73, 95%CI[ -0.88, -0.59], P<0.01), psychological flexibility (MD=-2.17, 95%CI[-2.77, -1.57], P<0.01) and quality of life in cancer patients (MD=5.27, 95%CI [3.57, 6.98], P<0.01). Conclusion ACT can relieve anxiety and depression, improve psychological flexibility and quality of life, and positively promoting physical and mental health of cancer patients.