Forest store significant amount of carbon and carbon stock in living tree biomass is amongst the largest carbon pools in forest ecosystems. Forest management practises, such as thinning, can improve tree growth, and increase carbon sequestration in forest ecosystems, thus be beneficial for achieving climate change mitigation goals. However, information about additional carbon stock increase as a result of thinning in the first 10 years is lacking in hemiboreal region. Therefore, this study investigates the additional carbon stock of the most common tree species (Scots pine, Norway spruce, and Silver birch) on mineral soils in hemiboreal forest of Latvia, focusing on the effects of thinning 5 and 10 years after. The aim of the study was to evaluate the effect of first commercial thinning on gained additional carbon stock of living tree biomass. Our results show, that thinning has a positive effect on additional carbon stock and timely performed thinning is crucial for the best outcome. Performing thinning in a timely manner results in a significantly higher additional carbon stock, as trees exhibit a more pronounced response, with biomass production peaking at younger age. Positive effect of thinning on additional carbon storage decreases with the age. This study provides valuable insights into the nuanced relationships between the tree species, stand age, and the temporal effects of thinning on carbon accumulation. The observed trends underscore the importance of forest management strategies that consider both species-specific traits and stand age for effective climate change mitigation.