The cellular senescence and functional decline of stem cells are primary contributors to the reduced regenerative capacity and weakened disease resistance in aged tissues. Among the various factors involved, oxidative stress resulting from the accumulation of reactive oxygen species (ROS) is a key driver of stem cell senescence. In an oxidative environment, cells continuously generate ROS, which accelerates cellular senescence and leads to functional deterioration. To intervene in the cellular senescence process of stem cells under such conditions, we selected bone marrow mesenchyme stem cells (BMSCs) as the model system and developed ROS-responsive selenium (Se)-containing Nano-micelles capable of efficiently scavenging intracellular ROS. The optimal formulation was determined by modulating the selenium content. Analysis of cellular senescence markers and regenerative capacity reveals that Nano-micelles containing 8% Se (Wt %), at a concentration of 15 µg/mL, can significantly modulate ROS levels in BMSCs under oxidative stress, thereby effectively delaying cellular senescence and preserving the osteo genic differentiation potential of BMSCs. These findings offer a promising strategy for mitigating stem cell senescence.