Ambrosio captivated onlookers in a seductive silver gown that hugged her figure in all the right places.
The model has been hanging out in the French Riviera all week, joining other models and A-list actors and actresses at various events.
The film festival finishes up on Sunday, May 26.
Last month she celebrated her 32nd birthday with her fiance Jamie Mazur. The couple have two children, Anja Louise, 4, and Noah Phoenix, 11 months.
Check out more ph...
The actress has struggled with her weight and found that sprinkling the brand's flavor-enhancing crystals on her food has helped her drop pounds.
She explained, "I've tried nearly every diet out there, and none of them worked for me. If you tell me I can't eat something, I'll obsess over it and end up overeating. SENSA is the perfect tool for me... I just shake it on my food to help me eat less and lose weight, and, more importantly, I feel great and am a healthier...