The low performance of listed deposit money banks has been attributed to poor corporate governance structures, leading to high-risk financial activities driven by the self-interest of managers. In light of this, this study examines the effect of ownership structure on financial performance of listed deposit money banks in Nigeria. An ex post facto research design was adopted for the study, with data obtained from secondary sources such as the annual reports of sampled firms and the Factbook of the Nigerian Exchange Group for a period of 2018–2022. The study population comprised thirteen (13) sampled deposit money banks listed on the Nigerian Exchange Group as of December 31, 2022. The entire listed 13 deposit money banks were selected as a sample size using the census sampling techniques. The data were analyzed using descriptive statistics and panel regression analysis techniques. The study’s findings revealed that institutional ownership has a negative and significant effect on the financial performance of listed deposit money banks in Nigeria. Foreign ownership has a positive and significant effect on financial performance of listed deposit money banks in Nigeria, while managerial ownership has a negative and significant effect on financial performance of listed deposit money banks in Nigeria. It is concluded that ownership structures significantly influence the market share of these banks. The study recommends that management should implement a policy allocating a portion of company shares to institutional investors. This could help align institutional interests with those of the business and enhance market stability. Also, government regulators should consider approving broader foreign ownership policies to stimulate performance improvements in their countries. This study has practical policy implications for managers to learn strategies to mitigate agency-related conflicts and optimize financial performance for listed deposit money banks in Nigeria, ultimately fostering sustainable growth and shareholder value.