According to Entertainment Tonight, Clooney debuted at No. 40 on the list based on earnings and celebrity appeal.
Absent from the list this year are regulars Cameron Diaz and Renee Zellweger.
Actor Jim Carrey, who once topped the list, is no longer present.
Leonardo DiCaprio were nowhere to be found, but his former flame, supermodel Gisele Bundchen is at No. 35.
Actresses Cate Blanchett and Jessica Alba both also made the list.
Photos: George Clooney
The annual Celebrity 100 list will be in this month's issue of Forbes, on newsstands Friday.