The 81-year-old Weaver led the Orioles to four American League pennants and the 1970 World Series championship.
The statue shows him with his hands stuffed in his back pockets.
Saturday's ceremony was part of the ongoing 20th anniversary celebration of Camden Yards. His statue stands in the Garden of the Greats picnic area behind centre field next to a statue of Hall of Fame star Frank Robinson, the focus of a similar ceremony in April.
Statues of Hall of Fame members Brooks Robinson, Jim Palmer, Eddie Murray and Cal Ripken Jr. will be unveiled later this season. Frank Robinson, Palmer, Murray and Ripken were in attendance Saturday.