Public diplomacy is taken to be one of the effective means to achieve the objectives of the foreign policy of the Islamic Republic of Iran. The position of Imam Khomeini and his role as the Grand Leader of the Islamic Republic of Iran is of great significance in introducing and directing public opinion and establishing relations with other nations and states as far as the Islamic Revolution and the ruling system of the Islamic Republic of Iran is concerned. In this article, in providing an answer to this main question that ‘What role has Imam Khomeini played in improving, fostering and making more efficient the public diplomacy of the Islamic Republic of Iran in ordrer to maintain and secure the interests of Iran and the world of Islam?’, this thesis was examined and the conclusion was made that, regarding the fact that Imam Khomeini’s high position in the politico-legal structure of the state and his high rank of religious authority and guardian jurist has played a decisive role in improving and fostering public diplomacy of the Islamic Republic of Iran and in taking further steps to increase its efficiency through engaging in discourses, accreditation, persuasion and image management. Furthermore, organizations and institutions involved in such enterprise can have this capability (capacity) and strategy to advance the objectives of public diplomacy of our Islamic nation and to increase the extent of its efficiency.