Psoriasis vulgaris is a human leukocyte antigen (HLA)-C*06:02-associated skin disease. Because of a strong linkage disequilibrium with other genes of the HLA-locus the role of HLA-C*06:02 in psoriasis pathogenesis as well as the mechanisms leading to lesional psoriatic T-cell activation were still unresolved. Accordingly, an autoimmune pathogenesis of psoriasis had remained hypothetical. We addressed these two interrelated questions using a Vα3S1/Vβ13S1 T-cell receptor (TCR) obtained directly from a tissue infiltrating CD8+ T-cell clone of an HLA-C*06:02-positive psoriasis patient by single-cell TCR analysis. Through reconstitution of this TCR in a reporter T-hybridoma cell line, we generated a reliable tool to determine the specificity of the lesional psoriatic T-cell response. Using this TCR hybridoma in a coculture system with other cell types, we discovered that the Vα3S1/Vβ13S1 TCR specifically recognized melanocytes in an HLA-C*06:02 restricted manner. By combinatorial peptide library screening, we identified ADAMTS-like protein 5 (ADAMTSL5) as an HLA-C*06:02-presented melanocytic autoantigen of the Vα3S1/Vβ13S1 TCR. Consistent with the Vα3S1/Vβ13S1-TCR reactivity, double/triple immunofluorescence staining revealed CD8+ T cells in psoriasis lesions attacking melanocytes that express ADAMTSL5. Thus, HLA-C*06:02 mediates an autoimmune response against melanocytes through autoantigen presentation and likely predisposes to psoriasis via this newly identified autoimmune pathway. Our study represents the first occasion where the unbiased analysis of a human TCR from tissue-infiltrating T cells could uncover HLA restriction, target cells, and an autoantigen in a human autoimmune disease. Exploring the specificity of the Vα3S1/Vβ13S1 TCR we demonstrate that the pathogenic relevance of an autoantigenic peptide has to be proven in the context of the full-length parent protein. This may require expression in the actual target cell type. Overall, our data provide conclusive evidence for the autoimmune nature of psoriasis.