<p>Maritime pollution mitigation is hindered by the high costs of clean port technologies, despite government subsidies aimed at encouraging their adoption. The impact of these subsidies on port competition and technology uptake remains poorly understood. This study employs a game-theoretic model to analyze emission reduction strategies under four subsidy scenarios: no subsidy, unilateral subsidy, bilateral subsidy with cooperation, and bilateral subsidy with non-cooperation. Our findings indicate that unilateral subsidies exacerbate disparities in clean technology adoption, leading to uneven pollution reduction outcomes. In contrast, bilateral subsidies result in higher profits and greater implementation of clean technologies. Notably, non-cooperative competition under strong subsidy conditions drives the deepest emission cuts due to intensified market rivalry for environmentally conscious shippers. These results provide critical insights for policymakers designing effective subsidy schemes and for ports strategizing under competitive and regulatory pressures.</p> Graphical Abstract <p></p>