Fraud in public institutions, particularly in financial management, remains a major challenge that weakens transparency, accountability, and public trust while causing significant financial losses. This study examined the effectiveness of forensic accounting techniques, specifically data mining and ratio analysis, in detecting and preventing fraud within the Nigerian public sector, focusing on the Office of the Accountant General of the Federation (OAGF) and related institutions. A survey research design was adopted, utilizing a structured closed-ended questionnaire administered to 200 staff members from the Budget and Accounts Office of the OAGF. Data were gathered from both primary and secondary sources and analyzed using simple percentages and T-test statistics. Findings revealed a significant positive relationship between data mining and fraud detection (t = 10.643, p < .0001), as well as ratio analysis and fraud detection (t = 13.666, p < .0000). The study concludes that forensic accounting techniques play a crucial role in strengthening fraud detection in public institutions. It recommends increased staff training and capacity building in forensic accounting practices and the adoption of integrated fraud detection systems to improve transparency, strengthen financial oversight, and reduce fraud risks in Nigeria’s public sector.