The eighth-season runner-up will serve as the musical mentor on the ninth season's April 13 performance episode before performing his latest single "Whattaya Want From Me" during the next night's live results show, a 19 Entertainment spokesperson confirmed to Entertainment Weekly on Tuesday.
It is still unknown what the musical theme will be for the Top 8 finalists during the week in which Lambert serves as mentor, according to EW.
The 19 Entertainment spokesperson was confirming recent reports that Sony Music representative had contacted certain radio stations to inform them of Lambert's American Idol return.
"Whattaya Want From Me" -- the second single of his debut album "For Your Entertainment" -- currently sits at No. 20 on Billboard's Hot 100 single sales chart.