The earliest settlers to this region were brought from New Hampshire by the Quaker leader, Nicholas Austin in the 1790s.
The county is located in the Eastern Townships, one of the 12 regions of Quebec.
Notable physical features of the county include Mount Brome in the northwestern corner of the Township of Brome and the much larger Mount Sutton in the Township of Sutton, and Brome Lake in the eastern part of the Township of Brome, which flows into the Yamaska River, site of a famous duck farm.
Owl's Head and Sutton are well-known ski hills.
A small part in the northwest were transferred to the Regional County Municipality of La Haute-Yamaska.