San Mateo is a census-designated place in Cibola County, New Mexico, United States. The population was 161 at the 2010 census.
San Mateo was founded when the Conquistadors came to New Mexico in the 1540s. The community has a Catholic church, a Baptist church, a Morada, a cemetery, and an old abandoned elementary school. It is also coined "the Uranium Capital of the World".
San Mateo is located at 35°19′53″N 107°38′35″W / 35.331423°N 107.643110°W (35.331423, -107.643110). The community is 25 miles (40 km) from Grants, the largest city in Cibola County. It overlooks Mount Taylor. San Mateo lies 7313 feet (2229 m) above sea level.