Carbon monoxide (CO) is an important indirect greenhouse gas, but its terrestrial sinks and sources are poorly understood. We present the first CO flux measurements using the eddy covariance method in an Arctic peatland. Our results show that CO fluxes are dominated by two processes: radiation-driven emissions and soil uptake. Dry peatland areas acted as CO sinks, while wetter areas were CO sources. Our findings suggest that current global models may underestimate Arctic CO emissions.