Del Rio signed a four-year contract, according to NFL Media Insiders Ian Rapoport and Albert Breer.
Del Rio replaces Dennis Allen, who was fired in September. Interim head coach Tony Sparano led the team for the final 12 games of the season, compiling a 3-9 record.
Del Rio has led Denver's defense for the past three seasons. He was the Jacksonville Jaguars head coach from 2003 through 2011, leading the franchise to two playoff trips and a 68-71 regular-season record.
Del Rio reportedly met with Raiders owner Mark Davis during the Broncos' postseason bye week and was made available for a second interview after Denver was eliminated by the Indianapolis Colts in the AFC Divisional Playoff on Sunday.
In the past 11 seasons, Oakland has had eight different head coaches and has not posted a winning record. The Raiders have not made the playoffs since 2002.
- Scooby Axson