AbstractOsteosarcoma (OS) is the most common malignant bone tumor and is prevalent in adolescents. In clinical studies, miR‐210 has been reported to be tightly correlated to the poor prognosis of OS. Nevertheless, its roles in OS have not been fully elucidated. In view of the central role played by OS stem cells (OSCs) in the malignant progression of OS, this study investigated the influence of miR‐210 on the formation of OSCs. Our previous findings suggested that the microenvironment of bone, abundant TGF‐β1 and hypoxia, could induce OS cells to dedifferentiate into OSCs. In this study, we found that miR‐210 participated in the dedifferentiation of OS cells into OSCs, and inhibiting it significantly suppressed the formation of OSCs. Further results suggested that miR‐210 promoted the expression of TGF‐β1 and its downstream effectors Snail1 and Slug which were highly elevated in the process of OS dedifferentiation. Additionally, the target gene of miR‐210 was also investigated. It was found that NFIC was significantly reduced by miR‐210 treatment and also during OS dedifferentiation. Therefore, this study suggested that miR‐210 promoted OS cells dedifferentiation and uncovered its role in the malignant progress of OS.