Born in Sligo, Ireland, the son of Henry Mulvey and Barbara McGee, Mulvey was a teacher starting at the age of 16 in Irish National School system and the schools of the Church Educational Society.

In 1856, he emigrated to Canada East at the invitation of Egerton Ryerson, the superintendent of education for Canada East, settling in Haldimand County where he was a teacher and editor of the local newspaper.

In 1870, he joined the Red River expeditionary force and left for Winnipeg.

During the North-West Rebellion, he served as a major in the 95th Battalion (Manitoba Grenadiers).

In the 1882 election, he ran unsuccessfully for the House of Commons of Canada for the electoral district of Selkirk.