The '4 Minutes' singer topped a poll by America's Forbes magazine after making £73 million in the past year, mainly thanks to her sold-out 'Sticky and Sweet' world tour and lucrative endorsement deals.
Celine Dion came second after earning £66 million in the first year since returning to the road following her three-year residency in Las Vegas.
Beyonce Knowles made £58 million in the past 12 months, coming third in the poll, after releasing an album, starring in two films and embarking on a 110-date world tour.
Other musicians in the poll include Coldplay and Bruce Springsteen, who is in the middle of a world tour which will see him headline at the world famous Glastonbury music festival on Saturday (27.06.09) and play at London's Hyde Park on Sunday (28.06.09).
In order to compile the list of the year's top earning musicians, the magazine considers money made from album sales, touring, publishing and endorsement deals from June 2008 and June 2009.