Sumner was born in Manchester, New Hampshire on December 5, 1873, to parents Charles D. Sumner and Orintha A. Thompson. He was raised a Baptist but was confirmed as an Episcopalian during college. He was educated at the public schools of Manchester, later received a bachelor's degree in science from Dartmouth College in 1898, after which he worked for the Western Electric Company. He studied for the priesthood at Western Theological Seminary, and graduated in 1904. He was also awarded a Doctor of Divinity from Northwestern University.^{[1] [2]}

Sumner was ordained to the diaconate on November 7, 1903, and to the priesthood on May 29, 1904 by Coadjutor Bishop Charles P. Anderson of Chicago.^[3] Sumner was in charge of St. George Mission, Grand Crossing, Illinois. By 1906 he became Dean of the Cathedral of St Peter and Paul in Chicago.^[4] Sumner was elected Fourth Bishop of Oregon, on September 16, 1914, serving until his death in 1935. He was consecrated on January 6, 1915.^{[5] [6]}

Sumner died on September 4, 1935, in the Good Samaritan Hospital in Portland, Oregon. He was buried in Manchester, New Hampshire.^[7]