Shariah governance provide strike conformity with Islamic businesses ethics and the expectation of its customers which aim at improving firms performance and societal welfare to eliminate poverty in the global setting. The purpose of this study is to investigate the impact of Shariah governance on Islamic banks (IBs) performance of 31 IBs of 4 countries of South Asia for the period of 2010-2016 and developed a CG index for IBs. Two types of analysis were performed; descriptive statistics and panel random effects model. It was found that IBs of Bangladesh gets higher ICG scores due to their larger Shariah boards, corporate boards, board independence and board meetings compare to others countries. The results of the model show that larger Shariah and corporate boards are value enhancing. The study suggests that considering the progressive stage and complexity of competition of IBs with historically mature and financial sound CBs, larger boards with strategic vision may provide IBs the competitive edge in the market.