The amfAR gala is the biggest fundraising event at the world's largest film festival. The benefit was first hosted by Elizabeth Taylor.
The list of stars attending Thursday's event included DiCaprio, Cannes jury members Nicole Kidman and Christopher Waltz, singers Kylie Minogue and Janet Jackson, and actors Adrien Brody, Jessica Chastain and Goldie Hawn.
The evening featured performances by gold-clad Shirley Bassey singing "Goldfinger" and British pop band Duran Duran.
Introducing the event, supermodel Heidi Klum said it raised more than 10 million euros ($12.9 million) a year for AIDS research.
Other auction items included tickets to Hollywood events, a Damien Hirst painting, an Annie Leibovitz family portrait, the chance to star in four movies and a private performance from Simon Le Bon and John Taylor of Duran Duran.