The San Pedro Riparian National Conservation Area (SPRNCA) protects approximately 60 linear kilometers (km) of the San Pedro River within the Madrean Sky Islands region of southeastern Arizona. This cottonwood-willow (Populus fremontii-Salix gooddingii) gallery forest habitat with perennial surface flow is unique from the Chihuahuan mesquite desert and supports a wide diversity of plant and animal life. Mountain lions (Puma concolor) were hypothesized to use the SPRNCA as a temporary habitat while moving between neighboring mountain ranges. Using remote camera traps located on desert washes that drain the Huachuca Mountains, we demonstrated that mountain lions use the riparian corridor as part of their resident home range. We recorded 53 independent observations (mean of 1.47 observations per 100 trap nights) of mountain lions with at least 30 minutes between sightings during our study between September 2019 and May 2021. Mountain lions were found using riparian habitat in all seasons and photos were taken of young kittens within 0.3 km of the San Pedro River. Preferred prey species (Coue's white-tailed deer [Odocoileus virginianus couesi] and javelina [Pecari tajacu]) have been observed often within the SPRNCA. Future research should explore the connectivity and metapopulation structure of mountain lions within the SPRNCA and neighboring mountain ranges.