He was born near Salem, Ohio. In 1877, he moved to Pennsylvania with his parents, who settled in Allegheny, Pennsylvania (now part of Pittsburgh). He attended Allegheny High School and studied Medicine for two years, after which he studied law. He was admitted to the bar in December 1893 and commenced practice in Pittsburgh. He was city solicitor of Allegheny from 1903 to 1906. He was chairman of the Republican State convention in 1912.

Porter was elected as a Republican to the Sixty-second and to the nine succeeding Congresses and served until his death. He was the Chairman of the United States House Committee on Foreign Affairs during the Sixty-sixth through Seventy-first Congresses. He was an unsuccessful candidate for Mayor of Pittsburgh in 1913. He was appointed in 1921 to represent the United States House of Representatives on the advisory committee to the Washington conference on armament limitations, and he represented the United States at the centennial of Brazil’s independence, in 1922. He was a member and chairman of the American delegation to the Second International Conference on Opium, at Geneva in 1924 and 1925, although he unexpectedly withdrew the American delegation prior to the Conference's conclusion. The American delegation's proposals for more stringent drug control were rejected.

Porter also served as chairman of the House Committee on Foreign Affairs, in which capacity he drafted the "Porter Resolution", passed by the House, which authorized the President to place the United States' relations with China on a footing of equality. He was also chairman of the Foreign Service Buildings Commission from 1926 to 1930. He died in Pittsburgh and was interred in Highwood Cemetery.