Blanchett celebrated her 39th birthday on Wednesday
Cate Blanchett, Sean Penn and a host of stars have graced the red carpet as the Cannes Film Festival opened with a gala screening of dark drama Blindness.
Cast members Gael Garcia Bernal, Danny Glover and Julianne Moore were on hand to launch Fernando Meirelles' film.
The black tie event came at the end of a first day that saw a host of stars descend on the French seaside resort.
However, the talk of the Croisette was all about Jack Black letting slip that Angelina Jolie was having twins.
In a joint interview with Black, the actress then confirmed she was expecting twins with partner Brad Pitt.
The US stars were promoting animated feature Kung Fu Panda, which is screening out of competition.
Critics will get their first look at the film on Thursday morning ahead of its own premiere.
Jolie also appears in Clint Eastwood's film The Changeling, one of 22 in contention for the prestigious Palme d'Or.
Natalie Portman, Faye Dunaway and Eva Longoria were among the other celebrities who attended the opening night gala.
Moore and Bernal star in Blindness, which opened this year's festival
Also present were Bollywood actress Aishwarya Rai, actor Dennis Hopper and X-Files star Gillian Anderson.
Thursday sees Hunger, a film by first-time British director Steve McQueen, open the festival's secondary competition, Un Certain Regard.
The film portrays the last weeks in the life of IRA hunger striker Bobby Sands, who died in prison after refusing food for 66 days in 1981.
Highlights of the next 11 days include the world premiere of the new Indiana Jones film, in which Blanchett appears.