It remains unclear that long noncoding RNAs' role in cancer initiation and progression, including osteosarcoma. Long noncoding RNA LINC00963 was found to be participated in carcinogenesis and progression of osteosarcoma. However, the molecular mechanisms of LINC00963 engaged in osteosarcoma (OS) still needs to be explored. LINC00963 and miR-204-3p RNA expression levels were quantified by PCR in OS tissues and cells. CCK 8 assay, wound healing assay and transwell migration and invasion assay were chosen to assess cell growth, viability, migration, and invasion. Luciferase reporter assays were performed to verify direct interaction between LINC00963 and miR-204-3p and miR-204-3p and Fibronectin-1. Western blot was conducted to evaluate Fibronectin-1 expression in OS cells. LINC00963 was verified to be highly expressed in OS samples and cells. Specifically, elevated expression of LINC00963 was correlated with poor prognosis in patients. Furthermore, LINC00963 overexpression was found to promote proliferation, migration, and invasion . The luciferase reporter assay showed that LINC00963 can suppress miR-204-3p by directly binding miR-204-3p. Rescue experiment results indicated that function of LINC00963 in osteosarcoma was miR-204-3p dependant. Besides, we initially explored Fibronectin-1 (FN1) as the target of LINC00963/miR-204-3p axis in osteosarcoma. Our findings implied that LINC00963/miR-204-3p/FN1 can play an important role in proliferation and progression in osteosarcoma. LINC00963 has the potential to be a therapeutic target for osteosarcoma treatment.