It is therefore important to understand how firms financing choice affect their performance. The kernel of this study is to examine the impact of firms' financing choice on their profitability in Nigeria capturing both the effects of internal and external factors that drive firms' profitability. The result of the study has many intrinsic values and deemed to benefit the external investors and shareholders who will be able to know how the finance structures affect their performance. Lenders may find the results useful in evaluating the firms' performance before giving loans and finally, academicians who will see new empirical evidence particularly in the finance literature emanating from an emerging economy like Nigeria.