<p>Psychological stress is increasingly recognized as an important determinant of human skin health, but the molecular and epigenetic mechanisms by which it affects the epidermis are still not well understood. To investigate whether psychological stress is associated with molecular differences in the epidermis, and how these might relate to skin phenotypes, we performed a multi-omics study in 60 stressed and 60 relaxed young adults. From lower-back epidermal samples, we generated DNA methylation profiles and RNA-seq data, and additionally measured skin cytokines and skin phenotypes. We identified 289 differentially methylated probes and 10 differentially expressed genes associated with psychological stress. Integration of methylation and expression with a functional epigenetic module approach yielded seven network modules; enrichment analyses of DMP-annotated genes and module genes revealed significant enrichment of terms related to glutamatergic synapse and synaptic signaling, in line with the emerging concept of a cutaneous neuroendocrine system. None of the 36 tested skin cytokines differed significantly between groups after correction for multiple testing. Skin darkening scores were higher in the stressed group. A CpG site in the <i>SERPINA1</i> promoter and <i>SERPINA1</i> expression were associated with this phenotype, and mediation analysis suggested that <i>SERPINA1</i> expression partly mediated the association between cg01431455 methylation and skin darkening. Taken together, our study links psychological stress to coordinated differences in epidermal DNA methylation and gene expression, highlights glutamatergic and <i>SERPINA1</i>-related pathways as candidates for further mechanistic study, and establishes an epidermal multi-omics dataset for future work on stress–skin interactions.</p>