Regional expansion in Indonesia is the division of an area into two or more regions. The main objective of regional expansion is to improve the welfare of the community through enhanced public services, accelerated regional economic growth, and expedited management of regional potential. This research aims to analyze the essence of regional expansion and its relation to regional autonomy, as well as regional expansion from the perspective of justice and the balance of authority. This research is a normative legal study with a conceptual and legislative approach. The research results show that the essence of regional expansion and its relation to regional autonomy as an effort to realize and optimize regional autonomy. Regional expansion, when viewed from the aspect of justice, essentially emphasizes the fair and equitable distribution of resources, a transparent, accountable, and participatory decision-making process, effective and restorative conflict resolution, and the enhancement of equal opportunities for all members of the community. In terms of the balance of authority, regional expansion can serve as one means to achieve a balance of authority, particularly in relation to efforts to strengthen decentralization within the framework of the Unitary State of the Republic of Indonesi
