<p>Inland water vessels are a substantial but poorly quantified source of transport-sector CO₂ emissions. Using approximately 20 billion automatic identification system records and a trajectory completion algorithm, we provide a global high-resolution assessment of inland vessel CO₂ emissions. These vessels emitted 164.0 ± 1.58 TgCO₂ in 2022, equivalent to 24.7% of global waterborne vessel emissions, despite operating on only 0.4% of the global navigable marine and inland water surface area. Emissions are concentrated within a few hotspot river corridors and exhibit baseline-dependent amplification (2019–2022) together with seasonal variability. These patterns reflect the combined effects of transport demand and hydroclimatic constraints on navigability. Because inland water vessel emissions occur within river corridors where riverine CO₂ evasion is also active, they represent an important anthropogenic carbon source and may influence river–atmosphere CO₂ exchange. These results provide a basis for improving inland transport emission inventories and informing targeted mitigation strategies under climate change.</p>