The Raiders are planning a news conference Tuesday to introduce Gruden as their next head coach.
Gruden will replace former Raiders coach Jack Del Rio, who was sacked Sunday after a disappointing six-win season.
Jon Gruden is returning to the sideline with the Oakland Raiders and will be rewarded with a contract that is the longest and richest for any coach in National Football League history, multiple media outlets reported Friday.
The news conference was first reported by the Raiders Snake Pit website. Gruden has already started putting together a staff with Cincinnati defensive co-ordinator Paul Guenther among those expected to join.
Gruden, now a Monday Night Football analyst, coached the Raiders from 1998 to 2001, winning AFC West titles in his last two seasons.
Oakland had previously traded Gruden to Tampa Bay for four draft picks after Gruden spent four seasons with the team.
Steve Corkran of RaidersSnakePit.com first reported the news. He went on to win Super Bowl XXXVII with the Tampa Bay Buccaneers in 2002. He has a 95-81 career record. "I know they've gone through their process of interviewing candidates and until they're done I won't know".
This would not mark the first time the Raiders brought back a coach for a second stint.