The deal is reportedly $100 mil for 10 years, the longest coaching deal in National Football League history according to Adam Schefter.
Gruden will replace former Raiders coach Jack Del Rio, who was sacked Sunday after a disappointing six-win season.
Raiders reporter and author Steve Corkran first reported on the Raiders' plan for a "splashy" Tuesday news conference.
Oakland's press conference will come after Gruden makes his final appearance for ESPN on Saturday when the Kansas City Chiefs host the Tennessee Titans. After leading the Raiders to 8-8 records his first two years, Gruden helped the team reach the AFC title game following the 2000 season and got Oakland back into the playoffs the following season.More news: Ryan Shazier has feeling in legs, father says
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In 2002, Gruden was traded to Tampa Bay, where he coached the Buccaneers to a Super Bowl victory over the Raiders the following season. Gruden accumulated a 38-26 overall record as the Raiders coach and was 2-2 in playoff games during his four seasons.
The last time Gruden coached the Raiders was January 19, 2002 against the New England Patriots.
Several assistant coaches have already been hired by the Raiders in anticipation of Gruden's hiring.
"We believe the Rooney Rule was complied with".
Other teams have also done it, with one of the most recent notable coaching hires being Joe Gibbs in Washington.