SNAI1, an epithelial-mesenchymal transition (EMT)-inducing transcription factor, promotes tumor metastasis and resistance to apoptosis and chemotherapy. SNAI1 protein levels are tightly regulated by proteolytic ubiquitination. Here, we identified USP37 as a SNAI1 deubiquitinase that removes the polyubiquitination chain from SNAI1 and prevents its proteasomal degradation. USP37 directly binds, deubiquitinates, and stabilizes SNAI1. Overexpression of wild-type USP37, but not its catalytically inactive mutant C350S, promotes cancer cell migration. Importantly, depletion of USP37 downregulates endogenous SNAI1 protein and suppresses cell migration, which can be reversed by re-expression of SNAI1. Taken together, our findings suggest that USP37 is a SNAI1 deubiquitinase and a potential therapeutic target to inhibit tumor metastasis.