Objective The aim of this study was to explore the potential role and regulatory mechanism of microRNA (miR)-222-3p in oral squamous cell carcinoma (OSCC). Methods The expression level and prognostic significance of miR-222-3p was detected in OSCC tissues. CCK-8, transwell, and flow cytometry assays were used to explore the effect of miR-222-3p on cell proliferation, migration, invasion, and apoptosis. The influence of miR-222-3p on cyclin-dependent kinase inhibitor 1B (CDKN1B) expression was evaluated by luciferase assays, real-time polymerase chain reaction, and Western blot. Results We found that miR-222-3p was overexpressed in OSCC tissues, comparing with normal tissues. Kaplan-Meier curves showed that OSCC patients with high expression of miR-222-3p (P = .003) showed worse overall survival than those patients with low expression of miR-222-3p. Multivariate analysis showed that miR-222-3p (P = .037) expression was an independent prognostic factor of OSCC patients. miR-222-3p promoted cell proliferation, migration and invasion and induced the apoptosis of SCC-15 and Tca-83 cells. Furthermore, luciferase reporter assays indicated that CDKN1B is targeted by miR-222-3p in OSCC cells. Overexpression of CDKN1B inhibited OSCC cell proliferation, migration, and invasion and promoted cell apoptosis rate. Conclusions miR-222-3p affects OSCC cell proliferation, migration, invasion, and apoptosis through targeting CDKN1B, and may be a potential prognostic biomarker for OSCC patients.