This study investigates the effect of forensic auditing and whistleblowing on corporate fraud prevention in Nigerian deposit money banks, with whistleblowing examined as a moderating variable. Using a positivist philosophy and a survey–correlational research design, primary data were collected from 150 staff across relevant departments in Nigerian banks using a structured questionnaire. Descriptive statistics, correlation analysis, diagnostic tests, and Ordinary Least Squares (OLS) regression were employed for analysis. Findings indicate that forensic auditing significantly enhances fraud prevention through improved investigative capacity and internal control strengthening. Whistleblowing also positively and significantly influences fraud prevention, highlighting the importance of secure reporting channels and whistleblower protection. Furthermore, whistleblowing moderates the relationship between forensic audit and fraud prevention, reinforcing the effectiveness of forensic mechanisms when supported by internal disclosures. The study concludes that integrating forensic audit systems with robust whistleblowing frameworks enhances fraud mitigation. Practical recommendations and research limitations are provided.