Tumor necrosis factor-α-inducible protein-1 (TNFAIP1) plays a role in DNA synthesis, DNA repair, cell apoptosis and human diseases including cancer, and may be involved in tumor progression and metastases. However, little is known concerning the function of TNFAIP1 in human osteosarcoma (OS). The aim of the present study was to investigate the function and underlying mechanisms of TNFAIP1 in human OS. The expression of TNFAIP1 was examined by immunohistochemical assay using a tissue microarray procedure. A loss-of-function experiment was performed to explore the effects of lentiviral-mediated TNFAIP1 siRNA (siTNFAIP1) on cell proliferation, invasive potential and apoptosis by MTT and Transwell assays and flow cytometric analysis in OS (MG-63 and U-2 OS) cells. The results showed that the expression of TNFAIP1 protein was significantly increased in OS tissues compared with that in adjacent non-cancerous tissues (ANCTs) (73.3 vs. 48.9%, P=0.018), and was correlated with the distant metastasis of the patients with OS (P=0.029). Knockdown of TNFAIP1 suppressed cell proliferation and invasion, and induced cell apoptosis in the OS cells together with the downregulation of p65 nuclear factor-κB (NF-κB), proliferating cell nuclear antigen (PCNA) and matrix metalloproteinase-2 (MMP-2) and upregulation of caspase-3. Collectively, our findings indicate that high expression of TNFAIP1 is associated with distant metastasis of OS, and knockdown of TNFAIP1 inhibits the growth and invasion, and induces apoptosis in OS cells through inhibition of the NF-κB pathway, suggesting that TNFAIP1 may act as a potential therapeutic target for the treatment of cancer.