Plastic pollution in the world’s oceans threatens marine ecosystems and biodiversity, and ultimately people. The connected nature of the marine environment suggests that coordinated actions by countries sharing an ocean border may provide more effective pollution control than unilateral actions by any one country. However, economic theory and empirical evidence suggest that countries often fail to cooperate, even when joint economic benefits would be higher under cooperation. Here we present a modelling framework for determining the potential economic benefits of cooperative marine plastic pollution (MPP) management. The framework integrates an estimated plastic transfer matrix with game theory to derive the potential economic benefits of international cooperation for 16 countries bordering the North Atlantic Ocean. A fully cooperative outcome leads to a substantial reduction in MPP, resulting in significant aggregate net economic benefits. Similar findings apply under alternative scenarios and considering modelling uncertainties.