Carbon release from thawing permafrost receives ample attention since it may cause rising greenhouse gas concentrations in the atmosphere. However, we demonstrate through a 9-year lasting incubation experiment that thawing permafrost stabilizes a substantial amount of fresh plant litter carbon from increasing plant productivity for decades. Although litter carbon is faster decomposed than the permafrost carbon it may contribute to the build-up of organic carbon in thawing permafrost soils.