This study uses Taiwan Corporate Governance 100 Index to investigate the relationship between corporate governance and operating performance. In addition, this study examines if the announcement of corporate governance 100 (CG100) firms shows positive abnormal returns for the selected CG 100 firms. The sample consists of 774 listed firms, spanning the period from 2012 to 2014. Ordinary least squares regression results show that the link between corporate governance and operating performance is insignificant. However, customer awareness has a significant positive moderating effect on the link between corporate governance and operating performance, which implies that CG100 firms with higher customer awareness have a significant positive effect on operating performance. Event study finds that CG100 firms show significant, positive abnormal returns before the announcement of CG100 index, especially for CG100 firms with higher customer awareness.