Mental disorders are among the most poorly treated illnesses in sub-Saharan Africa. It is estimated that 70%–80% of South Africans consult traditional health practitioners for the treatment of psychological ailments. As traditional health practitioners maintain a strong role in assessing and treating patients with mental illness in this context, this study contributes to the burgeoning research literature on the topic. Semi-structured in-depth interviews were conducted with 18 traditional health practitioners in Johannesburg, South Africa, between January and May 2022. Interviews were transcribed and translated into English. The data were managed using NVivo 12 software and thematically analysed. Traditional health practitioners interviewed generally perceived mental illness to be of supernatural causation, either as a result of bewitchment, a calling for patients to become THPs themselves, due to displeased ancestors, or due to natural causes. Traditional health practitioners identified eight primary treatments that they use for treating mental illness. Among these were throwing of bones (tinhlolo) to start communicating with ancestors, steaming (ukufutha) to start a cleansing process, sneezing (umbhemiso) to forcefully dispel the spirit causing the illness, induced vomiting (phalaza), and the administration of laxatives (mahlabekufeni) to remove the spirits poisoning the body as well as animal sacrifice to purge spirits and communicate with ancestors. This is all followed by cutting (ukucaba), which is the final part of the treatment and ensures that the evil spirit cannot return. Due to the ubiquity of traditional health practitioner usage for mental illness in sub-Saharan Africa, it is essential to understand what conceptions traditional health practitioners have of the aetiology of these disorders as well as their modalities for administering treatment.