IL-17A has been strongly associated with epidermal hyperplasia in many cutaneous disorders. However, because IL-17A is mainly produced by αβ and γδT cells in response to IL-23, the role of T cells and IL-23 has overshadowed any IL-17A–independent actions. In this article, we report that IL-17A gene transfer induces epidermal hyperplasia in Il23r−/− Rag1−/−-and Tcrδ-deficient mice, which can be prevented by neutrophil depletion. Moreover, adoptive transfer of CD11b+ Gr-1 hi cells, after IL-17A gene transfer, was sufficient to phenocopy the disease. We further show that the IL-17A–induced pathology was prevented in transgenic mice with impaired neutrophil extracellular trap formation and/or neutrophils with conditional deletion of the master regulator of selective autophagy, Wdfy3. Our data demonstrate a novel T cell–independent mechanism that is associated with neutrophil extracellular trap formation and selective autophagy in IL-17A–mediated epidermal hyperplasia.