Glycyl-L-histidyl-L-lysine-Cu²⁺ (GHK-Cu) is a naturally occurring copper peptide with anti-aging properties. This investigation examines the effects of GHK-Cu on cellular senescence, DNA repair, and antioxidant capacity in primary human dermal fibroblasts. Treatment with GHK-Cu significantly reduced senescence-associated β-galactosidase activity, increased telomerase activity, and enhanced expression of antioxidant enzymes including superoxide dismutase and catalase.