The singer-and-actress is believed to put pen to paper on a contract worth just over $1 million to sit on the talent show's panel alongside Simon Cowell, L.A. Reid and Britney Spears, who is thought to be earning $15 million for her judging role, TMZ reports.
Simon believes Demi will be a hit with younger fans of the programme after starring in a number of Disney films including 'Camp Rock', 'Jonas Brothers: The 3D Concert Experience' and 'Barney & Friends' throughout her career.
The 19-year-old brunette has described her latest TV opportunity as a ''dream come true''.
She said: ''I'm so thrilled to join this legendary group of judges on the show. To be able to spend each week with Simon, L.A. and Britney watching the best that America has to offer is truly a dream come true.''
Demi and Britney were confirmed as replacements for Nicole Scherzinger and Paula Abdul on the panel in a decision announced at Fox's Upfront Presentation at the Beacon Theatre in New York last night (14.05.12).