For much of the history of American ornithology, hybrid birds discovered outside of known hybrid zones have presented an identification challenge—given the likely parental species are typically identified based on inferences from plumage patterns—but also a source of insight into evolutionary processes. With the advance of modern genetics, the tools are now available to definitively identify hybrids for which genetic samples are available and, in many cases, determine the identity and the sex of each parent species as well as F1 versus backcross status. Typically, these kinds of hybrids are rare; however, one apparently common hybrid wood-warbler (family Parulidae) are putative crosses between Mourning Warblers (Geothlypis philadelphia) and Common Yellowthroats (G. trichas), which have been reported at least thirteen times between 1955 and 2024, though never confirmed genetically. Here we describe the results of genetic and plumage analysis to identify a putative G. philadelphia x G. trichas hybrid captured in July, 2017 in New York, USA. We used genotype likelihoods derived from whole-genome sequencing data of the putative hybrid and several species in Geothlypis and Oporornis (the most likely genera of the parents) to confirm bird’s identity as an F₁ hybrid between G. philadelphia and G. trichas. We sequenced one mitochondrial gene and used publicly available sequences of several related species to identify the maternal parent as G. philadelphia. The data and code presented here and in GenBank are intended to permit reproduction of the analyses that made up the study, including processing reads, making trees, and running PCA and admixture.