This study focused on corporate governance and financial performance of parastatals in Nigeria. Five (5) banks were selected which are First Bank Plc, United Bank of Africa Plc, Guarantee Trust Bank Plc, Zenith Bank Plc and Fidelity Bank Plc. The data obtained to test and validate the hypotheses were from secondary sources concerning the variables of interest. However, the data generated are as follows; 2015 – 2022 (8 years) financial statements of five sampled banks which provided information about the variables tested and discussed. The data analysis revealed that measures of financial performance (ROA, BOD & BS), recorded means and standard deviations of 0.021966, 13.8, 13.8 and 0.0136177, 2.988868, 2.988868 respectively. The low standard deviation recorded by each of the measures of financial performance suggests that the return on asset of the respective sampled banks, members of their board of directors and board size have proximity with their respective average values. The respective minimum values recorded for ROA, BOD and BS are 0.0025847, 2 and 2; whereas the maximum values were 0.0561668, 19 and 19 respectively. This implies that the minimum of all the measures is not below 0.0561668 and the maximum did not exceed 19. It is concluded that Board composition which entails Board of Directors and Board Size has no significant effect of the financial performance of firms. The study recommended that efforts to improve corporate governance should focus on the value of the stock ownership of board members, since it is positively related to both future operating performance and to the probability of disciplinary management turnover in poorly performing banks.