With the global incidence rate of cancer rising year by year, approximately 60–80% of cancer patients experience psychological disorders such as anxiety and depression, which seriously affect treatment compliance and quality of life. As the core force in the mental health care of cancer patients, family members play a significant role in their participation. They can not only improve patients’ psychological state through emotional support but also compensate for the nursing gap caused by limited medical resources. This article systematically reviews relevant research on family members’ participation in the mental health care of cancer patients, summarizing the characteristics and intervention effects of three modes: medical guidance-family execution, family-medical collaborative decision-making, and social support-family empowerment. The comparison reveals that the integrated nursing mode combining “medical guidance + family decision-making + social support” can compensate for the deficiencies of single modes. At the same time, it analyzes the current research issues, such as the dual challenges of family members’ nursing ability and psychological burden, imperfect medical guidance communication mechanisms, and insufficient integration of social resources. It also proposes future prospects for deepening personalized mode innovation, improving the support system, and strengthening long-term effect research, providing a reference for the practice of mental health care for cancer patients.