Introduction <p>Cancer is a major cause of death worldwide and laughter therapy is used as a complementary therapy for cancer treatment. This study aimed to investigate the effects of laughter therapy on psychological symptoms (stress, anxiety, and depression) and physical symptoms (pain, fatigue, and sleep quality) among cancer patients.</p> Methods <p>Eight databases were searched, with the search period was limited to April 2024. Quality assessment of the included randomized controlled trials was performed according to the criteria for evaluating randomized controlled trials in the Cochrane Handbook for Systematic Reviews of Interventions. The RevMan 5.4 software was used for the data analysis.</p> Results <p>Nine randomized controlled trials were included in this systematic review and meta-analysis. The quality of the included studies was relatively high. The results showed that laughter therapy can effectively improve cancer patients’ stress, anxiety, depression, pain, and fatigue, but has no effect on sleep quality.</p> Conclusions <p>Laughter therapy is a low-cost, easy-to-implement intervention that may have potential benefits in improving psychological symptoms (stress, anxiety, and depression) and physical symptoms (pain and fatigue) among cancer patients. Laughter therapy has the characteristics of high safety, strong interaction, and strong feasibility. It may promote communication between patients and between patients and medical healthcare, enhance the trust relationship between medical staff, and potentially improve the quality of life for cancer patients. Healthcare professionals should consider laughter therapy as a potential adjunctive therapy, but its implementation should be tailored to individual patient needs and supported by robust evidence.</p>