Introduction: With aging and growth of the population, the risk of cancer incidence and mortality is rapidly increasing. However, psychosocial treatment has been seriously neglected in many healthcare settings. Laughter therapy is a therapeutic program to improve emotional wellbeing and health which has been applied as a complementary treatment. We aim to explore effects of laughter therapy for patients with cancer on their negative emotions such as depression, anxiety, stress, pain, and fatigue. Methods: We searched the Cochrane Library, Embase, PubMed, Scopus, Web of Science, WANFANG data, Weipu (VIP), Chinese National Knowledge Infrastructure (CNKI) and independently rated the risk of bias in every article using the Cochrane Collaboration’s Risk of Bias Assessment Tool. Review Manager and STATA software were used to pool the individually included studies. Results: Seven studies were found eligible to be included in the present review. Overall, study quality was relatively high. Our findings suggest that laughter therapy might have a positive effect on improving emotional response in cancer patients. Arguably, laughter therapy, whether humor or laughter, has a positive effect on anxiety, stress, pain feeling, fatigue, and depression in cancer patients. Conclusions: Laughter therapy is a convenient, multi-modality, flexible-duration therapy to improve negative emotions in cancer patients, regardless of their gender, age, and type of cancer.