Born in Kinsale in 1780, he was the son of James Bowen (1740–1796), Staff Surgeon in the British Army, who died at Martinique. His mother, Isabella, was the daughter of Richard Sheffield Cassan of Sheffield, County Offaly, and his wife Isabella Hamilton, sister of the Rt. Rev. Hugh Hamilton, Bishop of Ossory. Educated at Drogheda Academy, Bowen came to Lower Canada in 1797, with his great-aunt Anne Hamilton, and her husband, Lt.-Colonel Henry Caldwell. He studied law and entered the offices of Jonathan Sewell. He was called to the bar of Lower Canada in 1803. Bowen served as Lieutenant and then Captain in the Quebec militia.