An unofficial vote count showed Ravenstahl had more than 63 percent of the vote, while Republican Mark DeSantis had about 35 percent, The Pittsburgh Post-Gazette reported. DeSantis had the largest percentage won by a Republican in more than 40 years in the Democratic city.
Ravenstahl is only 27, making him one of the youngest people to run a major U.S. city. He was president of the City Council when Mayor Bob O'Connor died in September 2006.
Both candidates were running for mayor for the first time.
Ravenstahl's victory gives him the last two years of O'Connor's term.