Using unique survey data to measure corporate integrity, we examine the relation between corporate integrity and internal control quality. The results show that corporate integrity is significantly and negatively associated with internal control weaknesses. We find a substitution effect between informal and formal institutions for improving internal control quality. In other words, the negative association between corporate integrity and internal control weaknesses is more significant when the legal development or market competition is weaker. Furthermore, we find that more effective corporate governance can strengthen the relation between corporate integrity and internal control quality. These findings indicate that corporate integrity can improve the quality of internal control. Our findings also provide empirical evidence for the construction of stronger internal controls.