He was the son of Union Army colonel Clement Warner, and the grandfather of Wisconsin state senator Fred A. Risser.
In 1904, Warner was elected to the Wisconsin State Assembly from Dane County's 1st Assembly district (the Towns of Blooming Grove, Dunn, Madison and Pleasant Springs, and the city of Madison) to succeed fellow Republican Matthew S. Dudgeon, receiving 3,761 votes to 2,926 for Democrat Joseph C.
Risser married Warner's daughter, Elizabeth, and served three terms in the State Senate as a member of the short-lived Wisconsin Progressive Party.
[3] On July 5, 1894, he married Lillian Dale Baker, a classmate at Madison High School and also at the University of Wisconsin.
[4] Ernest Warner, who had been president of the Madison Park and Pleasure Drive Association since 1912, died after an automobile accident in July 1930.