Preller has been assistant GM of the Texas Rangers. He has extensive international scouting experience, particularly in Latin America.
Preller replaces Josh Byrnes, who was fired June 22.
He beat out a field of finalists that included assistant GMs Mike Hazen of the Boston Red Sox and Billy Eppler of the New York Yankees, and Kim Ng, senior vice president for baseball operations for Major League Baseball. Ng is one of the highest-ranking women in baseball. There has never been a female GM in MLB or any of the other major sports. Ng also interviewed for the Padres' GM job in 2009 after Kevin Towers was fired. The job eventually went to Jed Hoyer.
Preller is setting the bar high for the Padres, saying he wants them to "to play on the big stage. ... The big stage is to play in the World Series, where the whole world is watching you."
San Diego has reached two World Series, in 1984 and 1998, losing both.
The Padres are looking for stability. They're on their third ownership group since 2009 and Preller is their fourth general manager since then.
San Diego has had only two seasons above .500 since winning consecutive NL West titles in 2005-06.
Although the Padres have been playing better since the All-Star break, they began the day 10 games under .500 and 12 games behind Los Angeles in the NL West.
Team President Mike Dee said Preller stood out in the interview process as a "difference maker" who will be able to bring "impact talent, championship-level talent" to the team.