The 'Diamonds' hitmaker bid USD 100,000 on a vintage print of late actress Elizabeth Taylor, the co-founder of amfAr, and USD 35,000 on diamond earrings during the benefit event, reported E!Online.
Justin Timberlake bought a Damien Hirst painting, while Miley Cyrus also bid on a print. All donations help fund amfAr's Aids research programs.
Gwyneth Paltrow hosted the gala and Cyrus made a speech about raising Aids awareness.
Rihanna, 26, later took to the stage to present the night's honouree, fashion designer Tom Ford, with his Inspiration Award.
Guests, who spent at least USD 3,000 on a ticket, also included Sharon Stone, Milla Jovovich, Kelly Osbourne, Lea Michele, Eddie Redmayne, Michelle Rodriguez, Kristin Davis and Kat Dennings.
