The identification of occupied habitat is an important component of recovery efforts for threatened and endangered species. The western population of the Yellow-billed Cuckoo (Coccyzus americanus), federally listed as a threatened distinct population segment, has long been considered a riparian-obligate, yet recent survey efforts in southeastern Arizona have documented cuckoos occurring in xeroriparian habitat during the nesting season. We investigated the distribution and breeding status of cuckoos in southeastern Arizona xeroriparian habitat by comparing the results of standardized call-playback surveys to the results of nest searching efforts in the same sites from 2018 to 2020. We then used this information to interpret more extensive survey data from 2013 to 2020 and develop an updated breeding distribution map for southeastern Arizona. We confirmed breeding in 94% of sites categorized as occupied according to survey results. Combining our data with previous survey data, we estimated a minimum of 100 occupied sites in southeastern Arizona xeroriparian habitat, representing a substantial increase in the known breeding population in Arizona. Occupied sites were concentrated in southern and western “Sky Island” mountain and foothill drainages, from 600–1800 m, with xeroriparian vegetation in a matrix of Madrean-evergreen woodland, semi-desert grassland, or desert scrub. Breeding by cuckoos in southeastern Arizona xeroriparian habitat is important for cuckoo conservation, but this habitat also faces potential threats from grazing, climate change, and development.