Health insurance fraud remains a significant challenge to healthcare financing, yet existing research in Nigeria has focused predominantly on public hospitals, with little attention given to private healthcare facilities. This study investigates how three selected private hospitals in Mowe, Ogun State, manage health insurance fraud, examining the types of fraud encountered, the strategies employed to address them, the challenges faced, and the solutions developed. Guided by Routine Activity Theory, the research adopted a case study and exploratory design. Primary data were collected through nine key informant interviews with representatives of Health Maintenance Organisations (HMOs), intelligence and investigating police officers, and pharmaceutical experts, alongside nine in-depth interviews with Chief Medical Directors, Financial Managers, and Administrative Officers. Secondary sources included books, journal articles, internet resources, and unpublished works. The findings revealed multiple forms of fraud such as falsified receipts, patient fraud under false identities, billing for services not rendered, ghost patient fraud, and overcharging for treatment. Hospitals responded with strategies including maintaining detailed health records, hiring adequate personnel, and raising community awareness. However, these efforts were constrained by challenges such as aggressive patients, poorly trained staff, and deliberate delays in claims approvals. In response, hospitals introduced measures such as designated verification offices, monthly financial audits, regular personnel training, collaboration with law enforcement agencies, and partnerships with regulatory bodies. The study concludes that while private hospitals in Mowe actively engage in health insurance fraud management, continuous adaptation and stronger institutional support are required to enhance the effectiveness and sustainability of these efforts.