He told The Associated Press in an interview Wednesday afternoon that he made up his mind to run in the fall, after spending months weighing support at events around the state.
Swann, a Hall of Fame receiver and longtime TV football commentator, faces three other candidates in seeking the Republican nomination for governor his first run for political office. The winner of the May 16 primary would likely face Democratic Gov. Ed Rendell, who is expected to seek a second four-year term.
If successful in his first bid for political office, Swann would become Pennsylvania's first black governor. His announcement was no surprise: His political committee has been raising money for his campaign for nearly a year.
Swann, 53, planned to kick off his campaign with a Wednesday night rally in Pittsburgh, followed by appearances in five other cities Thursday and Friday.
The Steelers won four Super Bowls during Swann's nine-year pro career with the team. He has worked for ABC Sports since his retirement from football in 1983.
Swann has so far revealed little about his political philosophy or the initiatives he would pursue as governor. He has advocated reducing certain business taxes and said he opposes abortion rights.
In independent polling, former Lt. Gov. William Scranton III and Swann are running ahead of the other two GOP candidates, but behind Rendell.
Swann said Wednesday that he hopes to convince blacks that he is a better candidate than Rendell, the former Philadelphia mayor. The Democratic Party has "taken the African American vote for granted," Swann said.
G. Terry Madonna, a pollster and professor at Franklin & Marshall College in Lancaster, said Swann needs to convince voters that he has ideas and the leadership ability necessary to turn them into policy. He could benefit from disenchantment with the state and national governments, Madonna said.
"Voters are looking for fresh faces," Madonna said. Swann "has a personal story to tell that's compelling."
The eventual GOP nominee could get a big boost Feb. 11, when the Republican State Committee meets to consider endorsing a candidate. On Wednesday, Scranton wrote Swann to ask him to participate in several debates before the meeting.