Born in the Liberty district of Frederick County, Maryland, Urner was educated in the common schools. He also attended the Freeland Seminary of Montgomery County, Pennsylvania, and Dickinson Seminary of Williamsport, Pennsylvania. He engaged in teaching in his native county from 1859-1862, studied law, and was admitted to the bar in 1863. He commenced practice in Frederick, Maryland, and served as State’s attorney for Frederick County from 1871-1875.

In 1878, Urner was elected as a Republican to the Forty-sixth and Forty-seventh Congresses (serving from March 4, 1879 - March 3, 1883). While in Congress, Urner served as the chairman of the Committee on Accounts (Forty-seventh Congress). He was not a candidate for renomination in 1882, and resumed the practice of his profession in Frederick. He became local attorney for the Pennsylvania Railroad Co. in 1887, and served as a member of the Maryland State Senate from 1888 until 1890. He was also appointed naval officer at the port of Baltimore by President Benjamin Harrison in 1890.

Urner engaged in banking and other business enterprises later in life, and became a trustee of several educational institutions. He died in Frederick in 1926, and is interred in Mount Olivet Cemetery.

This article incorporates facts obtained from the public domain Biographical Directory of the United States Congress.