AbstractHumans and animals frequently encounter high‐density crowding stress, which may accelerate their aging processes; however, the roles of gut microbiota in the regulation of aging‐related processes under high‐density crowding stress remain unclear. In the present study, it is found that high housing density remarkably increases the stress hormone (corticosterone), accelerates aging‐related processes as indicated by telomere length (in brain and liver cells) and DNA damage or inflammation (as revealed by tumor necrosis factor‐αand interleukin‐10 levels), and reduces the lifespan of Brandt's vole (Lasiopodomys brandtii). Fecal microbiota transplantation from donor voles of habitats with different housing densities induces similar changes in aging‐related processes in recipient voles. The elimination of high housing density or butyric acid administration delays the appearance of aging‐related markers in the brain and liver cells of voles housed at high‐density. This study suggests that gut microorganisms may play a significant role in regulating the density‐dependent aging‐related processes and subsequent population dynamics of animals, and can be used as potential targets for alleviating stress‐related aging in humans exposed to high‐density crowding stress.