The study examines the effect of internal audit on the financial performance of deposit money banks (DMB) in Nigeria. Specifically, the study ascertained the effect Audit Committee independence, Audit committee size, Audit committee gender diversity on the financial performance of deposit money banks. The study employ ex post facto research design. The sample size for this research work is 12 listed DMBs from 2010 – 2018. The sources of data employed in this study are secondary data from the Nigeria Stock Exchange Fact Books and related companies’ Annual Financial Reports for the period covered in the study. The study made use of spearman rank correlation analyze and also employed panel least square regression analyses in order to analyze the data for the study. The findings of this study indicated that audit committee independence has a negative insignificant effect on the performance of listed DMBs in Nigeria, audit committee size has a positive significant effect on the performance of listed DMBs in Nigeria, audit committee gender diversity has a positive insignificant effect on the performance of listed DMBs in Nigeria. The researcher recommends that there is need for banks to have an audit committee that is not too small such that there will be no lack of expert advice and too large such that it has free riders that are prone to follow other member’s opinion. The size of the audit committee should also be in a way that the process of accounting and finance are protected such that it will lead to increased performance.