This research examines the impact of corporate governance on firm performance, as well as it examines the indirect relationship through mediating environmental social responsibility between the corporate governance and firm performance. Panel data regression was performed on a sample of 66 non -financial firms in Egypt during the period from 2010-2018. The model parameters were estimated using generalized least square regression. Six corporate governance indicators (Ownership concentration, Female directorship, Role Duality, Board independence, Board size and Audit reputation) were chosen in testing the hypothesized relationship between corporate governance practices with firm performance, which was measured by return on asset, return on equity and Tobin's q. Moreover, environmental social responsibility factor is measured using the S&P/EGX ESG ratings Published index. The results show that environmental social responsibility partially mediates the relationship between audit reputation, role duality and ownership concentration with return on asset. Moreover, the results show that environmental social responsibility fully mediate the relationship between role duality and return on equity. On the other hand, the results show environmental social responsibility doesn't mediate the relationship between corporate governance and Tobin's q.