He was elected to the United States House of Representatives in 1962 from a newly created district based in Tampa after defeating segregationist Sumter de Leon Lowry Jr. in the Democratic primary and runoff elections, and was reelected 16 times. Gibbons voted against the Civil Rights Act of 1964, but in favor of the Voting Rights Act of 1965 and the Civil Rights Act of 1968. The district changed numbers three times during his tenure, from the 10th (1963–1967) to the 6th (1967–1973) to the 7th (1973–1993) to the 11th (1993–1997). He usually skated to reelection in what was generally reckoned as the only Democratic bastion on Florida's Gulf Coast. However, in 1992, he was held to only 52 percent of the vote by Republican Mark Sharpe. Two years later, he defeated Sharpe again, only winning by 4,700 votes.