DeJarnette was born in Caroline County, Virginia, and studied at Bethany College.

He was a member of the Virginia House of Delegates from 1853 to 1858, when he was elected as an Independent Democrat to the United States House of Representatives, with 50.45% of the vote defeating Democrat John Caskie, where he served from 1859 to 1861.

[1] His home, Spring Grove, was listed on the National Register of Historic Places in 1976.

[2] This article incorporates public domain material from the Biographical Directory of the United States Congress

This article about a member of the United States House of Representatives from Virginia is a stub.