In 1974, Luken won a special election[1] in the Cincinnati-based 1st congressional district to fill out the term of William J. Keating, a Republican who resigned his seat.[2] However, Luken was defeated later that year in his bid for a full term by Republican Bill Gradison, who had preceded him as mayor of Cincinnati. In 1976, Luken ran in the neighboring 2nd district and unseated Republican incumbent Donald D. Clancy, beginning service in 1977 (95th Congress). He was reelected six times, all by large margins. He was only the second Democrat to represent a significant portion of Cincinnati for more than one term in the 20th century.
In 1983, Luken and Gradison swapped districts as a result of the 1980 census, with Luken's district being renumbered as the 1st District. He did not run for an eighth term in 1990, opting instead to retire in favor of his son, Cincinnati mayor Charlie Luken, who won a term in his father's former seat.
Tom Luken's brother, Jim Luken, was a labor leader and also served as a Cincinnati mayor.