John Kenna was born on April 10, 1848, in Kanawha County, Virginia, which became part of the state of West Virginia in 1863. He had little education, and at the age of 16 he served with General Shelby in the Confederate Army and was wounded. After returning home, he read law and was admitted to the bar in 1870. He became very active in the emerging Democratic party of West Virginia.

He rose from prosecuting attorney of Kanawha County in 1872 to justice pro tempore of the county circuit in 1875, and to the United States House of Representatives in 1876. While in the House he championed railroad legislation and crusaded for aid for slack-water navigation to help the coal, timber, and salt industries in his state. These activities earned him a seat in the United States Senate in 1883, where he continued fighting for his two causes.

Kenna became Democratic minority leader and emerged as a powerful and controversial speaker on the issue of the independence of the executive branch of the government. He forcefully defended President Cleveland on several issues and indicted the Senate Republican majority for failure to pass tariff reforms. His brilliant career was cut short with his sudden death at the age of 45 on January 11, 1893.