Osteosarcoma (OS) is a high-grade, aggressive bone sarcoma. LncRNAs play a key regulatory role in controlling biological and pathological processes. The expression of lncRNA SNHG9 varies among different cancer tissues, and the role of SNHG9 in OS progression is unclear. In this study, we found SNHG9 overexpression in OS tissues and cells. In addition, downregulated SNHG9 expression impaired the proliferation, migration, and invasion abilities of OS cells. SNHG9 expression was positively regulated by the transcription factor SOX4. SNHG9 interacted with miR-214-5p as a molecular sponge and SOX4 was identified as the target of miR-214-5p. The interaction affected the expression of SNHG9, miR-214-5p, and SOX4, and regulated OS cell proliferation, migration, and invasion. Therefore, the SNHG9/miR-214-5p/SOX4 feedback loop performs an important role in OS progression and might be used as a new potential therapeutic target for the treatment of OS.