The 49-year-old Weiss oversaw several labels as president and CEO of the Zomba Label Group. He helped grow Jive Records from a small imprint to a major force with such blockbuster acts as Britney Spears, Usher, the Backstreet Boys, Justin Timberlake and 'N Sync. Recent successes include teen sensation Chris Brown and singer-songwriter T-Pain.
As head of BMG, Weiss will oversee RCA Records, Jive, J Records, LaFace, Arista, Volcano, Verity, GospoCentric and Fo Yo Soul.
Sony BMG said that Davis will continue to work with top artists in his new position as chief creative officer Sony BMG Worldwide.
Weiss, through a representative, declined comment on the promotion, and a representative for Davis was not immediately available when contacted by The Associated Press.
The company also announced that Charles Goldstuck, Davis' close associate and president and chief operating officer of the BMG label group, as well as Tim Bowen, Sony BMG's chief operating officer.
Davis became BMG's label group after successfully starting J Records and Arista Records; decades earlier, he was head of Columbia Records.
Davis has been credited with helping to launch the careers of acts like Whitney Houston, Janis Joplin and Bruce Springsteen, and breathing new life those of acts like Rod Stewart and Santana.
Alicia Keys, whose latest album "As I Am" has sold more than 2 million copies, was among his finds and recent protege Leona Lewis debuted at No. 1 on the Billboard album chart this week with more than 200,000 copies of her album sold in the first week.
Davis has also been influential in the careers of the winners of "American Idol," guiding their albums to mostly platinum successes. Last year, however, he disagreed with the direction of Kelly Clarkson's "My December," and she publicly criticized him; the album was a flop, and she later apologized.
BMG label group is overseen by Rolf Schmidt-Holtz, CEO of Sony BMG Music Entertainment.