This study was carried out for the purpose of understanding the impact of internal control on firm performance. This research wanted to prove that internal control played an important role on the performance of ten selected manufacturing firm in Nigeria. Internal control factors like board size, audit committee size, and board independence were investigated to see how they impact performance. Secondary data gotten from the ten manufacturing firms’ financial statement were analyzed using the panel data regression analysis. Although the fixed effect and the random effect regression were carried out, the Hausman test pointed to the fixed effect regression as significant, hence it was focused on. Findings from the fixed effect revealed that board size, audit committee size, and board independence were all significant in impacting firm performance measured by equity returns. The study therefore recommended among others that the Board of directors should be more diverse in the composition of board members as this would boost their independence.