He represented Pictou in the Canadian House of Commons as an Anti-Confederate and then a Liberal from 1867 to 1872 and from 1874 to 1878. He represented Nova Scotia in the Senate of Canada from 1898 to 1903. He began work in his father"s shipping and retail business and became owner during the 1850s.
He built ships and also transported goods by ship.
He was also involved in coal mining, the timber trade, a tannery and an iron foundry. Although he originally built wooden sailing ships, he later built steamers and pioneered the use and building of iron and steel ships in Nova Scotia.
Carmichael was also a lieutenant-colonel in the local militia. He was elected to the House of Commons in 1867 as an opponent of Confederation, but joined the Liberals in 1869.
He was reelected in 1874 and was named to the Senate in 1898, resigning shortly before his death in New Glasgow in 1903.