Osteosarcoma is the most common primary bone malignancy and arises primarily in the metaphyseal ends of long bones in children and adolescents. m iR-590 has been found to have anti-tumor effects in many other cancers. However, the role of miR-590-3p in osteosarcoma is poorly understood. In this study, we show that miR-590-3p was significantly decreased both in osteosarcoma tissues and cell lines, suggesting a potential role of miR-590-3p in osteosarcoma. Over-expression of miR-590-3p inhibited U2OS cell viability as shown by the CCK-8 assay and clonogenic assay. Ki-67 immunofluorescence staining and cell cycle analysis revealed that up-regulation of miR-590-3p inhibited U2OS cell proliferation. Transfection with miR-590-3p mimics suppressed PCNA, Cyclin D1 and CDK4 expression and increased p53 and p21 expression. In addition, U2OS cells transfected with miR-590-3p mimics exhibited reduced cell invasion and migration, characterized by the wound healing assay and transwell assay. Furthermore, bioinformatics analysis demonstrated that SOX9 was a potential target of miR-590-3p. SOX9 was up-regulated in osteosarcoma tissues. Transfection with miR-590-3p mimics markedly suppressed SOX9 expression both at the mRNA level and protein level. Dual luciferase assay validated the direct binding site of miR-590-3p on SOX9. Exogenous SOX9 expression in U2OS cells at least partially reversed the effects of miR-590-3p in U2OS cells. Enforced SOX9 expression restored cell viability in osteosarcoma cells transfected with miR-590-3p mimics. In addition, over-expression of SOX9 restored decreased cell metastasis properties caused by transfection with miR-590-3p mimics in osteosarcoma cells. In summary, these results indicated that miR-590-3p is an anti-cancer miRNA that can inhibit proliferation and metastasis in osteosarcoma cells. Our findings provide a novel insight into the biological function of miR-590-3p in osteosarcoma and SOX9 may be a potential therapeutic target for osteosarcoma.