Born in Ithaca, New York, Seymour graduated from Hamilton College in 1857 and read law to enter the bar in 1858.
He was a member of the North Carolina Senate from 1872 to 1874, and a Judge of the Superior Court in New Bern from 1874 to 1882.
[1] On February 14, 1882, Seymour was nominated by President Chester A. Arthur to a seat on the United States District Court for the Eastern District of North Carolina vacated by Judge George Washington Brooks.
Seymour was confirmed by the United States Senate on February 21, 1882, and received his commission the same day.
He served in that capacity until his death on February 19, 1897, in New York City.