The show's producers and actors began Saturday's festivities with a half-mile parade from the University of Scranton to Courthouse Square, the Philadelphia Inquirer reported Sunday.
Fans of the show -- some of whom drove all the way from Florida to be there -- crowded the parade route, yelling for their favorite characters and asking for autographs, the newspaper said.
The television show is shot in California and the only filming done in Scranton was the show's opening credits, shot by actor John Krasinski before the pilot even aired.
"It's obvious the city has really embraced the show," said Courtney Barrow, 19, a Pennsylvania State University student lined up along the parade route.
The daylong festivities wrapped up with a fireworks display at the Scranton RailRiders baseball stadium where star Steve Carell made a surprise late appearance, the newspaper said.
The series finale of "The Office" is scheduled to air May 16.