As few as 10% of companies have obtained significant financial results after implementing Six Sigma. This poor ability of achieving noteworthy financial benefits with Six Sigma initiatives has been attributed to leadership, even though no scholarly and empirical studies exist that discuss the theoretical foundation of leadership’s criticality for Six Sigma’s success. Thus, this quantitative study utilized a correlational research design to determine which leadership behaviors had significant relationships with organizational performance (OP) in a Fortune 500 company that nearly doubled its profits after implementing Six Sigma. The results showed that transformational leadership’s Inspirational Motivation (IM) and transactional leadership’s Contingent Reward (CR) had the greatest positive relationships with OP, while transactional leadership’s passive Management by Exception and Laissez-faire leadership had the most significant negative effects on the company’s performance. Additional research with other companies could enable generalization of this conclusion so that other companies could embed IM and CR leadership behaviors within their Six Sigma programs to reap significant financial enhancements.