John Morin was born in Philadelphia, PA. He moved with his parents to Pittsburgh, PA. He began work in a glass factory in 1882, and was employed in steel mills until 1885. In 1889 he moved to Missoula, MT and engaged in mercantile pursuits, during which time he took a night course at Haskins’ Business College at Missoula and was graduated in 1892. He returned to Pittsburgh and engaged in the hotel business. He was a director of the Washington Trust Co. since 1910. He served as a member of the Pittsburgh Common Council 1904-1906. He was a delegate to the Republican State conventions 1905-1912, and director of public safety in Pittsburgh 1909-1913.

He was elected in 1913 as a Republican to the 63rd Congress, and served eight terms. (March 4, 1913-March 3, 1929); He was Chairman of the Committee on Military Affairs in the 69th and 70th Congresses). He was an unsuccessful candidate for renomination in 1928. He was appointed a commissioner of United States Employees Compensation Commission in Washington, D.C., and served from 1928 until his death. He died in Marine Hospital, Baltimore, MD, and was interred in Calvary Cemetery, Pittsburgh, PA.