This study examined the relationship between leadership styles and business success of deposit money banks in Port Harcourt. A total of fifty-three (53) managers and supervisors were given the research instrument, however only fifty-two (52) responses were valid and used in the analyses. Two (2) testable null hypotheses were formulated and analyzed. Spearman’s Rank Order Correlation Coefficient was used to analyze the null hypotheses, with the help of Statistical Package for Social Sciences at 5% level of significance. The two null hypotheses were rejected and the alternate accepted. Indicating a significant positive relationship between the dimensions of leadership styles (transactional leadership and transformational leadership) and business success. It was concluded that transactional and transformational leadership styles, in which employees are allowed to have sense of belonging, carry out higher responsibility with little supervision, and followers are helped to achieve their visions and needs, enhances organizational performance. Consequently, it was recommended that the manager and supervisor of deposit money banks in Port Harcourt should: adopt a leadership/management approach that can accommodate all subordinates, irrespective of their personal and individual differences; and the communication channel between the management and the employees should always be in harmony. Information gap between the upper, middle and lower management should be avoided at all costs, so as to ensure coherency and synergy amongst the hierarchy of the firm.