The huge throng cheered as Mayor Edward Lee presented the Giants with the key to the city following a ticker-tape parade that began on Market Street near the Ferry Building and ended at Civic Center Plaza.
The Giants won their second World Series in three years Sunday with a 10-inning, 4-3 victory in Game 4 over Detroit, completing a dominating 4-0 sweep.
"Unfortunately for Detroit, with all due respect, they didn't know what they were in for," Giants General Manager Brian Sabean said.
But the easy World Series win only came after the Giants were forced to win six straight elimination games in the earlier rounds.
"If I had to pin a tag line on this team, it would be 'never say die,'" Giants Manager Bruce Bochy told the fans.
"There's one simple thing that happened with this team that hasn't happened enough -- it was sacrifice," added outfielder and clubhouse leader Hunter Pence. "They sacrificed their egos and played for (the fans)."