With the increasing frequency of ultraviolet (UV) exposure in daily life and the exploration of anti-photoaging strategies, natural plant-derived compounds with anti-skin-aging properties have garnered significant attention. This study aimed to evaluate the efficacy of zein-chitosan-based nanocarriers in enhancing the bioavailability of epigallocatechin gallate (EGCG) and to elucidate its mechanisms in ameliorating skin photoaging. Utilizing a Balb/c mouse model of photoaging, we monitored skin conditions, analyzed skin barrier function parameters, and observed changes in skin tissue structure and collagen fibers through hematoxylin–eosin (H&E) and Masson staining. Immunohistochemical staining was employed to assess COL1A1 levels in the skin, while enzyme-linked immunosorbent assay (ELISA) was used to measure antioxidant enzymes, inflammatory cytokines, matrix metalloproteinases (MMPs), and NF-kB levels. The effects of orally administered EGCG nanoparticles on UV-induced skin aging were investigated. UV exposure significantly increased skin roughness, impaired skin barrier function, thickened the epidermis, reduced collagen content, decreased antioxidant enzyme activity, and elevated levels of inflammatory cytokines, MMPs, and NF-kB in the model group compared to the normal control group. EGCG nanoparticles markedly ameliorated these photoaging manifestations, with some indicators showing superior improvement compared to free EGCG. These findings suggest that EGCG nanoparticles exhibit enhanced anti-photoaging effects over free EGCG, highlighting the potential of nanocarriers as a promising strategy to improve the bioavailability of EGCG.