He served on the town council for Saint-Polycarpe and also served as mayor.
Mousseau married Marie Rose-Avelina Cadieux.
He ran unsuccessfully for a seat in the House of Commons in 1887.
His election to the House of Commons in 1891 was overturned in 1892 and he was defeated by James William Bain in the two by-elections which followed.
He was the brother of Joseph-Alfred Mousseau.
His son Joseph-Octave was a member of the Quebec legislative assembly.