As the survival rates for prostate cancer (PCa) have improved, there has been an increasing focus on the mental health of couples affected by this condition. There have been several couple‐based psychological interventions, and yet the impact of this treatment modality on the mental health of PCa patients and their spouses is unclear. Consequently, a systematic search was conducted in PubMed, Embase, Cochrane, LILACS, and Web of Science up to March 2023 for randomized controlled trials (RCTs) addressing the impacts of couple‐based psychological interventions on both PCa patients and their spouses. Besides, the Cochrane Risk of Bias Assessment Tool was employed to evaluate the methodological quality and potential bias of the included studies. Moreover, statistical analysis and meta‐analysis were performed utilizing Revman 5.4, and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) was employed to assess the certainty of evidence. A total of nine RCTs were included, utilizing anxiety, depression, distress, communication, and self‐efficacy as outcome indicators to assess mental health. Results demonstrated that couple‐based psychological interventions increased spouses' self‐efficacy (WMD, 0.21; 95% CI: −0.00 ~ 0.42; P = 0.05) and communication (SMD, 0.34; 95% CI: 0.09 ~ 0.59; P = 0.009), while reducing their distress (SMD, −0.21; 95% CI: −0.40 ~ −0.02; P = 0.03). Nonetheless, there is a need for additional research on the effect of couple‐based psychological interventions on the mental health of PCa‐affected couples given the limited evidence supporting this conclusion.