El Rosario is a district of the Naranjo canton, in the Alajuela province of Costa Rica.
El Rosario was created on 14 January 1967 by Ley 4020. Segregated from San Miguel.
El Rosario has an area of km<sup>2</sup> and an elevation of metres.
For the 2011 census, El Rosario had a population of inhabitants.
The district is covered by the following road routes: