Originally from Green Valley, Glengarry County, Roméo Leroux studied at the University of Guelph, where he graduated in 1935. Hired as an agronomist by the Ministry of the Environment, he worked in the Sudbury area starting in 1935. He then became assistant director for the Northern Ontario agronomists, a position he held until he retired in 1966.
A talented popularizer, Leroux was instrumental in the foundation of cooperatives and the creation of the Association des producteurs de lait. He established cheese factories, demonstration farms, ploughmen associations, agricultural societies, as well as breeding and crop improvement clubs. As a bilingual popularizer, Leroux served Northern agriculture and Franco-Ontarian farmers.