STORY: Campbell, who on Sunday celebrated her 52nd birthday, wore a dramatic black gown featuring feather details and a plunging neckline.
Gyllenhaal, festival jury member Deepika Padukone, Spanish actor Rossy de Palma and model Emily Ratajkowski also opted for black outfits, with Padukone wearing a sequinned number.
Veteran actress Sharon Stone dazzled in an emerald green, bejewelled, strapless dress.
Floral accents were in vogue as well, with flowery dresses and tulip-heeled shoes adorning the red carpet.
Monday's red carpets were held for in-competition screenings of South Korean mystery "Decision to Leave" and David Cronenberg's "Crimes of the Future".
The film festival concludes on Saturday (May 28), when the winner of the prestigious Palme d'Or will be announced.