Background: Experts have been consistent that the overall functioning and productivity of individuals depend on their mental health status. The rising cases of mental health challenges are fast becoming a threat to public health, particularly in developing countries. Evidence shows that over 35% of the global population suffers mental health issues. The burden is higher in Sub-Saharan Africa, with Nigeria accounting for 13% prevalence. Earlier studies have demonstrated that complementary and alternative medicine (CAM) could effectively treat mentally ill patients and other chronic health problems. However, little is known about the caregivers’ attitudes, perceptions, and CAM utilisation in Nigeria. Method: 381 caregivers of mentally ill persons in Abakaliki were recruited into this study. The modified attitude toward Mental Illness Questionnaire was administered to the participants to elicit relevant information on CAM use. The data collected were analysed using descriptive statistics. Results: Most participants (92%) had good knowledge of CAM and would encourage their mentally ill relatives to use CAM. In comparison, 89% have either used CAM or used CAM on mentally ill relatives. CAM utilisation was associated with good knowledge and referral by other users. The common CAM therapies included herbal drugs, spiritual intervention, and alternative medical systems such as homeopathic medicine. It was concluded that the informal caregivers for mentally ill patients knew about CAM and were using them. Studies on the effectiveness and safety of CAM are required to establish their benefits in treating mental illness.