Researchers in international business have long been interested in understanding the impact of internationalization on performance and innovation. However, prior studies of this research stream offer mixed results. This study contributes to this research stream by employing agency theory to investigate how ownership concentration affects the performance and innovation implications of internationalization. Specifically, we examine two primary effects of ownership concentration: the incentive alignment effect, proxied by the controlling shareholder's cash flow rights, and the entrenchment effect, proxied by the divergence between control rights and cash flow rights of the controlling shareholder. Based on a sample of Taiwan's publicly listed firms, we find that the incentive alignment effect moderates the relation between internationalization and performance and innovation positively and the entrenchment effect moderates the relation negatively. These findings shed light on the mixed results of the literature. In addition, most countries outside the United States and the United Kingdom have high ownership concentration; therefore, our results may be generalizable to other settings, providing insight into the role of corporate governance in internationalization.