This study seeks to explore the relationship between internal corporate governance structures and firm financial performance in First Bank Nigeria Plc. The study used descriptive and inferential statistics. Data analysis for this study employed the multiple regression, descriptive statistical techniques that will be used are tables, frequencies, and percentages as well as mean and standard deviation. The result outcome signifies that size effect, corporate governance disclosure and financial reporting positively influence financial performance in First Bank Plc Nigeria. Therefore the study recommends the dire need by the regulatory authorities to instruct First Bank Nigeria Plc banks to obligate the strict application of the codes of governance in course of discharging their responsibilities, the study also recommend the need for a well-functioning whistle blower mechanism and the control of impartial practices should be observed and that can strengthen the application of corporate governance, lastly, the study recommends that financial reports available should be as current as possible and should be prepared as regularly as possible. This could be important to investors (both current and potential), employees, and even the management itself when it comes to decision making.