Montane red foxes (Vulpes vulpes ssp.) native to western North America are of broad conservation interest, occupying a narrow ecological niche and restricted to small, isolated populations across much of their distribution. Despite the need for robust information in guiding effective carnivore conservation, many aspects of montane red fox ecology are poorly understood due to their rarity. To improve ecological knowledge of Sierra Nevada red fox (V. v. necator), a montane red fox subspecies, we examined fox diet in an unstudied portion of their range in the central Cascades of Oregon, USA. In addition, we evaluated dietary overlap between montane red foxes and coyotes (Canis latrans), a presumably dominant carnivore that is expected to increase distributional overlap with montane red foxes under changing climatic regimes. We collected Sierra Nevada red fox and coyote scats via detection dog team surveys during 2017 in Oregon and used DNA metabarcoding to determine scat composition. Sierra Nevada red fox and coyote diets differed with respect to the most frequently occurring prey species and prey species that comprised the largest proportions of their diets (golden-mantled ground squirrel [Callospermophilus lateralis] and snowshoe hare [Lepus americanus], respectively). Despite some differences, Sierra Nevada red fox and coyote diets exhibited similar taxonomic richness and their dietary overlap was high (Pianka’s index = 0.74 via weighted percent occurrence, 0.69 via frequency of occurrence), with golden-mantled ground squirrel appearing to be an important prey item for both species. High dietary overlap suggests potential for competition between Sierra Nevada red foxes and coyotes where the two species occur sympatrically, which could be consequential for foxes in the future if spatial overlap indeed increases and results in niche compression. Our work addresses an aspect of data insufficiency for an imperiled species that can inform conservation strategies and species management.