Both TWIST and Wnt/β-catenin signaling reportedly play important roles in osteosarcoma development. In the present study, we explored the regulatory effect of TWIST on β-catenin in osteosarcoma cells and assessed how the functional interaction between TWIST and β-catenin would impact osteosarcoma cell survival against chemotherapy agent cisplatin. Overexpression and knockdown of TWIST were respectively performed in Saos-2 and MG-63 osteosarcoma cells. Overexpression of TWIST in Saos-2 cells significantly decreased the soluble β-catenin level, phosphorylation of glycogen synthase kinase-3β (GSK-3β) at serine 9, the mRNA level of β-catenin signaling target genes, and cell survival against cisplatin, which was strengthened by knocking down β-catenin. Knockdown of TWIST in MG-63 cells significantly increased the soluble β-catenin level, phosphorylation of GSK-3β at serine 9, the mRNA level of β-catenin signaling target genes, and cell survival against cisplatin, which was reversed by knocking down β-catenin or phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002. In conclusion, we demonstrate that TWIST decreases osteosarcoma cell survival against cisplatin by decreasing the soluble β-catenin level through a PI3K-dependent manner. This study provides the first evidence of a functional link between TWIST and β-catenin signaling in osteosarcoma cells, which adds fresh insights into the molecular mechanism of osteosarcoma development. © 2013 Wiley Periodicals, Inc.