The main objective of the study is to examine moderating effect of whistleblowing disclosure on related party transactions practices 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 creative accounting 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. In conclusion, the persistence of related party transactions practices in Nigerian deposit money banks highlights significant concerns for investors, regulators, and other stakeholders. The findings underscore the need for stronger regulatory frameworks, enhanced corporate governance, and more stringent enforcement mechanisms to promote ethical financial reporting and safeguard shareholder interests. As the banking sector continues to play a vital role in Nigeria’s economy, ensuring the integrity of financial reporting is essential for fostering sustainable growth, investor trust, and long-term value creation for shareholders. Based on the findings and conclusions of this study recommended that the role of whistle-blowing disclosure in promoting transparency and curbing financial misconduct cannot be overemphasized. It is recommended that Nigerian banks establish and enforce more effective whistle-blowing mechanisms. These mechanisms should provide secure and anonymous channels for employees and other stakeholders to report unethical practices without fear of retaliation. Furthermore, whistle-blowing outcomes should be disclosed publicly to ensure accountability and strengthen investor confidence and The Nigerian government should enact and enforce stronger protection laws for whistle-blowers in the banking sector. This includes legal protections to ensure that individuals who report financial misconduct are not subjected to retaliation, harassment, or job loss. Encouraging a culture of transparency through such protection will further bolster the role of whistle-blowing in mitigating the effects of related party transactions.