OBJECTIVES: As dental pulp therapy evolves towards regenerative approaches, biomolecules such as icariin, derived from Epimedium flowers, are being evaluated for their therapeutic potential. This study investigates icariin's effectiveness in promoting odontogenic differentiation in human dental pulp stem cells (hDPSCs) in vitro and as a pulp-capping agent in vivo. DESIGN: The study explored the effects of icariin on hDPSCs at concentrations of 10, 20, and 40 µM. Cell viability and migration assays were conducted to evaluate cytotoxicity and chemotaxis. Odontogenic differentiation was assessed using alkaline phosphatase staining and alizarin red S (ARS) staining, complemented by real-time PCR and Western blot analyses of key markers such as RUNX family transcription factor 2 (RUNX2), collagen type I alpha 1 chain (COL1A1), alkaline phosphatase (ALPL), and dentin sialophosphoprotein (DSPP). Additionally, the in vivo effects of icariin were tested in a rat maxillary molar model, where icariin-treated collagen sponges were used for direct pulp capping to evaluate its potential to induce reparative dentin formation. RESULTS: Icariin showed no cytotoxic effects on hDPSCs at any tested concentration, enhanced migratory activity in a dose-dependent manner, and significantly increased alkaline phosphatase activity and calcium deposition. Gene and protein expression analyses revealed a dose-dependent increase in odontogenic differentiation markers in icariin-treated hDPSCs. In vivo, icariin effectively promoted reparative dentin formation in exposed rat pulp. CONCLUSIONS: Icariin enhances odontogenic differentiation of hDPSCs and has promising potential as a pulp-capping agent for vital pulp therapy.