The team scheduled a news conference for Wednesday morning to introduce the new owners.
The sale was approved by major league owners on Aug. 16.
The new ownership group includes O'Malley's sons, Kevin and Brian O'Malley, and nephews Peter and Tom Seidler.
Golfer Phil Mickelson, a San Diegan, also is involved with the group. He won't be at the news conference, though, as he's en route to the Deutsche Bank Championship outside of Boston.
The group bought the Padres from John Moores, the majority owner since 1994.
The late Walter O'Malley bought the Brooklyn Dodgers in 1950 and moved them to Los Angeles before the 1958 season.
Peter O'Malley eventually took over for his father and all told under the family's ownership, the Dodgers won six World Series and 13 NL championships before being sold in 1998.
In comparison, the Padres have been to two World Series, losing in 1984 and 1998.
Ron Fowler, a local businessman, will become the executive chairman. Fowler had been a minority owner in the previous regime that ran the club, headed by Jeff Moorad. Moorad's attempt to buy the club on a layaway plan fell apart earlier this year, causing Moores to put the Padres back on the market.
The Padres have been back to the playoffs only twice since losing the 1998 World Series, and have won just one playoff game, in 2006.
San Diego entered Tuesday night's game against Atlanta on a season-high eight-game winning streak. Still, it was in fourth place in the NL West, 12 games behind the San Francisco Giants.