The receptor tyrosine kinase Ror2 plays important roles in mediating non-canonical Wnt5a signaling by activating the Wnt–JNK pathway and inhibiting the β-catenin–TCF pathway. It has been shown that Ror2 is phosphorylated and activated by casein kinase Iɛ when both molecules are over-expressed in cultured cells. However, it remains unknown whether or not Ror2 is phosphorylated upon Wnt5a stimulation. Here we show that Ror2 is phosphorylated on serine/threonine residues upon stimulation of cultured cells, expressing Ror2 endogenously, with Wnt5a, but not Wnt3a. It was found that treatment of cells with glycogen synthase kinase-3 (GSK-3) inhibitors (LiCl and SB216763) or small interfering RNAs (siRNAs) for GSK-3 (mainly GSK-3α) can inhibit Wnt5a-induced phosphorylation of Ror2. Immunoprecipitated Ror2 can also be phosphorylated by purified GSK-3α or GSK-3βin vitro, and ectopic co-expression of Ror2 and GSK-3 (mainly GSK-3α) in cultured cells results in Ror2 phosphorylation, irrespective of Wnt5a, that is sensitive to SB216763. These results indicate that GSK-3 is involved in Wnt5a-induced phosphorylation of Ror2. Moreover, it was found that Wnt5a-induced cell migration can be inhibited by SB216763 or by siRNA-mediated suppression of GSK-3α (and GSK-3β) expression, further emphasizing the role(s) of GSK-3 in Wnt5a-induced signaling.