The main objective of the study is to examine moderating effect of whistleblowing disclosure on Earnings management and shareholders’ value of listed deposit money banks in Nigeria.   The study used an ex-post facto design strategy, which entails analyzing events that have already happened, to guarantee a complete examination for this research. Census sampling technique was used to select all the 14 listed deposit money bank from the Nigerian Exchange Group (NGX) for financial statements spanning the years 2015 to 2025. The data was evaluated using regression analysis. In specifically, the Ordinary Least Squares (OLS) regression approach was employed to evaluate the effect of Earnings Management on shareholders' value in Nigerian listed deposit money banks employing e-views 9 software. The choice of the basic regression technique was based on its capacity to minimize the residual squares and its simple methodology. The findings confirm that while Earnings Management may offer short-term gains in terms of stock prices, dividends, and market perception, it ultimately undermines long-term shareholder value. Practices like income smoothing and earnings management can mislead investors about the true financial health of banks, resulting in increased market volatility and diminished investor confidence once discrepancies are uncovered. Related party transactions, if not properly disclosed, exacerbate conflicts of interest and contribute to the erosion of shareholder wealth. Based on the findings and conclusions of this study, several recommendations that Regulatory bodies such as the Central Bank of Nigeria (CBN) and the Securities and Exchange Commission (SEC) should enhance their oversight and enforcement mechanisms to ensure compliance with accounting standards and transparency in financial reporting. More stringent penalties for manipulative accounting practices, including tax manipulation and related-party transactions, should be introduced to deter unethical behavior and factor in the erosion of shareholder value is the lack of financial literacy among investors. To protect their interests, it is recommended that investors be provided with more education on how to interpret financial statements, identify potential red flags in earnings quality, and assess the long-term sustainability of firms. This can be achieved through training programs, workshops, and easy-to-understand reporting.