A landlocked 5th class municiplaity, Bagulin is located in the central eastern part of La Union Province. It is bounded on the north by San Gabriel Municipality,
on the east by Benguet Province, on the south by the towns of Burgos and Naguilian, and on the west by San Fernando City.
The town has a total land area of 107 square kilometers and is politically subdivided into 10 barangays.
Bagulin can reached by land via a road from Naguilian town. It is around 31 kilometers away from San Fernando City, the provincial capital, and 62 kilometer northwest of Baguio City.