San Mateo is a district of the San Mateo canton, in the Alajuela province of Costa Rica.
San Mateo has an area of km<sup>2</sup> and an elevation of metres. It is located in the coastal lowlands near the central Pacific coast, 31 kilometers east of Caldera Port, 44 kilometers southwest of the provincial capital city of Alajuela and 53 kilometers from the national capital city of San Jose.
For the 2011 census, San Mateo had a population of inhabitants.
The district is covered by the following road routes: