While migration studies scholars have paid considerable attention to internal migration within Indonesia, as well as to international labour migration flows from Indonesia, they have rarely considered the intersections between these two processes. This article addresses this gap through a close analysis of migration flows in one of Indonesia’s key transit areas – the Riau Islands. We argue that in the borderlands the processes of internal and international migration are mutually constitutive. The Riau Islands’ status as a transit zone for international labour migrants and as a destination for internal migrants determines its demographic profile and policies of migration control. Bordering practices are strongly influenced by the fact that not everyone who comes to the Riau Islands has the intention of moving on, and not all international migrants returning to the Islands intend to go home. Our analysis demonstrates that internal migration cannot be understood as a solely national phenomenon, and that international migration cannot only be explained by push and pull factors in sending and receiving destinations. These complexities necessitate research and policy responses that take into account the unique character of the transit provinces, and the role that their geographic location plays in the formation of multi-ethnic communities and the management of migration.