Colton Dixon, DeAndre Brackensick, Heejun Han, Jeremy Rosado and Joshua Ledet returned to the show to perform a medley of Bee Gees songs in memory of Gibb, who passed away earlier this month at the age of 62.
The performance featured the tracks 'Words', 'How Deep Is Your Love', 'How Can You Mend a Broken Heart' and 'To Love Somebody'.
Meanwhile, images of Gibb were projected onto a large screen on the stage.
Tributes were also paid to Gibb at the Billboard Awards last weekend, while Beyoncé and John Travolta are among the stars who have recently expressed their condolences.
Earlier this week, Barry Gibb posted a video montage online in tribute to his late brother.
Watch the American Idol tribute to Robin Gibb below:
Gallery - Robin Gibb, a life in pictures:
Copyright: Rex Features Jim Fenwick/Newspix