ABSTRACT This paper aims to analyse the impacts of cross-border activities and cooperation in the conflict management process in the Sulu-Sulawesi Sea. Using a qualitative approach with a case study method, this research collected longitudinal data from 2016 to 2022 through observation, interviews, and literature reviews. The results indicate that inter-state conflict can be managed through cooperation in political-economy and socio-cultural aspects instead of defence and security concerns. Legal and traditional cross-border cooperation have played important roles in conflict management by reducing violence and the practice of transnational crimes, increasing the welfare of transnational communities, and building good relations among cross-border actors. Several factors have supported these roles, prominently cultural proximity and trade interdependence which encourage diaspora and business networking. However, this research also identifies illegal cross-border activities that have negative impacts on conflict management by increasing tensions and disrupting regional stability.