Añasco is located in the Western Coastal Plains adjacent to Mayagüez. It is bordered to the north with Rincón, Aguada and Moca; to the south with Mayagüez, to the east with San Sebastián and Las Marías, and to the west with the Mona Canal.

River(s): Grande de Añasco, Cañas, Casey, Dagüey, Hondo, and Humatas

Ravine(s): La Balsa, Caguabo, Cerro Gordo, Cercada, Chiquita, Grande, Icacos, Justo, Las Piedras y Del Muerto