This study investigated the multifaceted benefits of Desmodesmus pannonicus water extract across various cell lines, including murine B16F1 melanoma cells, human keratinocyte HaCaT cells, and human follicle dermal papilla cells (HFDPCs), to assess its potential in skin health improvement. Initially, the antioxidant capacity of the extract was evaluated using the ABTS assay, revealing significant radical scavenging activity, indicating strong antioxidative properties. Subsequently, D. pannonicus extract showed notable inhibition of α-MSH-enhanced melanin production in B16F1 cells without cell toxicity by suppressing tyrosinase expression. Furthermore, the extract significantly promoted cell migration and enhanced wound healing in HaCaT cells, accompanied by an upregulation of VEGF and MMP mRNA levels, which are crucial for the wound healing process. In addition, we investigated the effect of D. pannonicus extract on hair growth-related genes in HFDPCs. Despite a slight reduction in VEGF mRNA levels, an increase in CTGF and HGF1 mRNA levels was observed, alongside a significant down-regulation of TGFβ1, highlighting the extract’s potential to promote hair growth and exhibit antiandrogenic effects. Collectively, these findings demonstrated the therapeutic potential of D. pannonicus extract in treating hyperpigmentation, enhancing wound healing, and promoting hair growth, making it a promising candidate for future dermatological applications.