We examine the implication of CEO hubris on the performance of Nigerian firms. Our study reveals that the determinants of hubristic managers like age, tenure, ownership, and political appointment adversely affect firm performance in the country. We propose that regulatory agencies of government should reduce; the age bracket of CEOs and the percentage of shares owned by CEOs. Besides, firms should not be allowed to make people with political connections or those who have once or presently in a political office a CEO because of its adverse effect on firm performance. Our study contributes to the extant literature on CEO hubris in at least two ways. First, we extend CEO hubris's implication on performance to Nigerian firms, since extant studies on firm performance in the country assume CEO rationality. Besides, existing studies on CEO hubris are from the eastern and western worlds. We take into consideration of the multidimensional nature of CEO hubris and firm performance than existing literature.