He was born in Saint-Jean-Chrysostome, Lower Canada, the son of Alexis Demers and Josephte Bessette. He was a notary clerk for his uncle Narcisse Demers. Demers was also a justice of the peace and captain in the militia. He was secretary-treasurer and then mayor for Saint-Georges d'Henryville. Demers was married twice: to Marie-Julie Brazeau in 1849 and to Marie Goyette in 1855. He was reelected in 1886 but died in office eight days later at the age of 61 in Henryville.