With the end of the Cold War and changes in the material and ideational structures of world politics, human society in the 21st century is witnessing the emergence of a new diplomatic paradigm. A typical example is public diplomacy, which has emerged as a great strategic option for not only great powers but also middle-powers, with the increasing importance of soft power. As such, not only the great change in the content and method of diplomacy, but also the diversification of the diplomatic actors can be seen as innovative in the context of a paradigm shift in diplomacy. In particular, the emergence of diplomacy at the sub-national level such as local government, especially city diplomacy, is a very interesting phenomenon. This study aims to examine the city diplomacy of Busan in the context of paradiplomacy. This paper also subsequently draws future challenges and implications for Busan’s city diplomacy.