Background Integrating mental health care into the primary care system is an important policy option in the Democratic Republic of the Congo (DRC). From the perspective of the integration of mental health care in district health services, this study analyzed the existing demand and supply of mental health care in the health district of Tshamilemba, which is located in Lubumbashi, the second largest city of the DRC. We critically examined the district’s operational response capacity to address mental health. Methods A multimethod cross-sectional exploratory study was carried out. We conducted a documentary review (including an analysis of the routine health information system) from the health district of Tshamilemba. We further organized a survey to which 591 residents responded and conducted 5 focus group discussions with 50 key stakeholders (doctors, nurses, managers, community health workers and leaders, health care users). The demand for mental health care was analyzed through the assessment of the burden of mental health problems and care-seeking behaviors. The mental health care supply available was described. Finally, the district’s operational response capacity was assessed. Results Analysis of technical documents indicated that the burden of mental health problems is a major chalenge in Lubumbashi. However, the proportion of mental health cases among the general patient population seen in the outpatient curative consultations in the Tshamilemba district remains very low, at an estimated 5.3%. The interviews not only pointed to a clear demand for mental health care but also indicated that there is currently hardly any offer of care available in the district. There are no dedicated psychiatric beds, nor is there a psychiatrist or psychologist available. In this context, the main source of care for people remains traditional medicine. Conclusion The gaps in the management of mental health problems constitute a major challenge in the DRC in general and in the health district of Tshamilemba in particular. Testing the feasibility of integrating a basic package of mental health care into existing primary care services is therefore of great relevance. Such a policy may contribute to strengthening the health system and enhancing people’s access to quality mental health care.