Talking about the strapless dress, which featured a low-cut neckline, the actress said: "It's sexy, isn't it!
"I had to have it made because you know how it is for us tall girls. It's impossible to find anything in a store," she said with a giggle.
Complimenting the pure white creation, Uma – who is in Cannes as a member of the festival's jury – wore an emerald green pair of Chopard drop-earrings.
Following in her fashion footsteps and embracing the minimalist colour trend was Faye Dunaway in an ivory kaftan-style floaty number, and Indian actress Aishwarya Rai in a stone, asymmetrical embellished Elie Saab gown.
And Salma Hayek sported a shimmering, off-white Gucci gown embellished with beads, crystals and sequins.
Her pleated, bodiced creation perfectly accentuated her hourglass figure, her side-swept tresses oozing Hollywood glamour.
Meanwhile, injecting a good dose of colour into the proceedings was Rachel McAdams, who chose a Rihanna-esque, peek-a-boo look for the glittering event.
Her scarlet silk, embroidered organza dress was red carpet-perfect, featuring a tulle ruffle skirt with a long, nude-coloured train.
The intricate Marchesa gown was paired with Bulgari jewellery and gold Casadei sky-scrapers, whilst the Notebook actress' big, cascading curls and side parting oozed old Hollywood.
Also dazzling on the red carpet was supermodel Karolina Kurkova in an Armani Privé gown that shimmered beautifully with atlantic blue sequins arranged in a wave motif.
Adding to the glittering effect were clear Swarovski crystals, stopping just short of the neckline which was fashioned from organza and crinoline.