This study examines how multiparty collaboration strengthens the institutional capacity of the National Border Management Agency (BNPP) in managing border areas in West and North Kalimantan, Indonesia. Border governance in these regions is characterised by fragmented authority, weak inter-agency coordination, and limited involvement of non-state actors. Existing studies on border management largely emphasise security or decentralisation perspectives, leaving limited empirical explanation of how collaborative mechanisms operate institutionally, particularly in developing country contexts. Employing a qualitative explanatory approach, data were collected through in-depth interviews, direct observations, focus group discussions, and document analysis conducted between August and November 2024. The findings reveal that BNPP’s coordinating capacity is strengthened through four interrelated collaboration mechanisms: coordination, integration, synchronisation, and simplification, supported by information and communication technology (ICT). ICT functions as an institutional enabler that enhances communication, reduces fragmentation, and facilitates cross-level governance. The study contributes to collaborative governance literature by demonstrating how a coordinative public agency with limited formal authority can enhance institutional capacity through ICT-enabled multiparty collaboration. Policy implications emphasise strengthening BNPP’s coordinating mandate, institutionalising non-state actor participation, and expanding ICT capacity at the local level.