This article provides the first logical analysis that detailed the process of comparative analysis between the correlation of board determinants’ quality and the financial performance of conventional and Islamic banks. However, in previous research, we have never encountered rewarding studies that compared these impacts. In our study, we distinguished between the impact of the board of directors on the financial performance in conventional and Islamic banks. Settings of the financial performance and board of directors of the conventional and Islamic banks are collected from 30 countries located in four continents: America, Europe, Asia, and Africa. Two equal samples were collected that each of them is composed of 112 banks. By using the cylindrical panel method, data were used to explore the impact of the board of directors on the financial performance between both types of banks over the period 2010-2018, giving us 1008 bank-year observations in each sub-sample. On the whole, empirical results have shown that in conventional banks the board of directors has negatively affected the financial performance, while the impact of the board on the financial performance of Islamic banks is ambiguous. Nevertheless, the degree of the positive impact on financial performance is more significant in Islamic banks.