He represented L'Islet in the Legislative Assembly of Quebec from 1878 to 1881 as a Liberal.
He was born in Montmagny, Lower Canada, the son of Charlemagne Couillard Dupuis and Charlotte Boilard, and lived at Saint-Roch-des-Aulnaies.
Couillard Dupuis was defeated when he ran for reelection in 1881.
His daughter Paméla married Pamphile-Gaspard Verreault, who represented L'Islet in the Quebec assembly from 1867 to 1878.
His grandson Louis-Auguste Dupuis also served in the Quebec assembly.