The rocker's name has been linked to the program for weeks but Tyler recently revealed he hadn't signed an official contract, insisting the whole idea was just "a work in progress."
But tonight AccessHollywood.com reports that a source close to the "Love in an Elevator" singer says the deal is done.
If the story is true, Idol producers appear to have agreed to hand over a large sum of cash to their new judge - Tyler recently said show bosses would have to "lay out the bread" to sign him up for the show's 10th season.
Cowell quit the show in May and was followed out the door by one-season judge Ellen Degeneres. Jennifer Lopez was in talks to replace the comedienne but reports suggest negotiations have stalled.