Decorin (DCN) is a member of the small leucine-rich proteoglycan family within the extracellular matrix, playing a role in the growth and development of hair follicle (HF). Exosomes serve as significant mediators of intercellular communication and are involved in the cyclic regeneration of HF. Exosomes derived from dermal papilla cells (DPC-Exos) are essential for the cycling and regrowth of HF. The present study demonstrated that DCN treatment significantly enhances the proliferation of DPCs, thereby promoting hair follicle growth. miRNA sequencing revealed 442 differentially expressed exosomal miRNAs. The regulatory mechanism of exosomal miR-129-2-3p, an up-regulated differential miRNA, was further investigated. The study identified its role in transporting DPCs to HFSCs through DPC-Exos. miR-129-2-3p has been shown to suppress the expression of genes associated with HF growth and development, lower the expression of genes and proteins downstream of the TGF-β signaling pathway, promote HFSC proliferation, and decrease HFSC apoptosis. Furthermore, miR-129-2-3p displayed an antagonistic effect on activating the TGF-β/SMAD3 signaling pathway induced by SRI-011381. The findings indicate that DCN-mediated DPC-Exos influence HF growth and development through the miR-129-2-3p/SMAD3/TGF-β regulatory axis. These results may facilitate novel strategies for the diagnosis and treatment of human hair disorders, in addition to enhancing industrial wool production.