We use a process-based biogeochemistry model to simulate the fire impacts on soil thermal and hydrological dynamics and carbon budget of forest ecosystems in Northern Eurasia during 2003–2016 based on satellite-derived burn severity data. We find that fire severity generally increases in this region during the study period. Simulations indicate that fires increase soil temperature by 0.2–0.5 °C through removing the ground moss and surface soil organic matter, especially in Asian part of the region. Fires also increase water runoff by about 131 million m³ yr^-1 through reducing post-fire evapotranspiration, leading to a higher regional river discharge. Fires remove 1.7 Pg C of ecosystem carbon through combustion emissions during this period and reduce net ecosystem production from 106.4 to 66.1 Tg C yr^-1. Fires lead the forest ecosystems to lose 2.3 Pg C, shifting the forests from a carbon sink to a source in this period. Our study highlights the importance of wildfires in affecting soil thermal and hydrological and carbon dynamics in boreal forests.