The 41-year-old former Miss World presented a relaxed self in the sleeveless net dress, which she teamed up with her hair side-swept in loose curls.
The mother of one kept her look minimal by going easy on accessories and instead concentrating on make-up. She paired her gown with heavily lined eyes and wine lip shade.
The "Devdas" star, who is accompanied by her three-year-old daughter Aaradhya at the 68th Cannes Film Festival, will also unveil the first look of her Bollywood comeback project "Jazbaa" with director Sanjay Gupta at the event tomorrow.
Earlier in the day, the actress attended United Nations Women's panel discussion on gender equality in the film industry.
She even did a shoot for L'Oreal Paris with Longoria, Natasha Poly and Li Bing Bing and the ladies had a fun afternoon together on set.
Other Indian celebrities who graced this year's red carpet at Cannes include Katrina Kaif, Sonam Kapoor and Mallika Sherawat.