The talented 24-year-old went for full-on glamour in a breathtaking Valentino strapless ball gown that was covered in beautiful embellishment.
With her hair slicked back and wearing little make-up except for a flash of colour on her lips, the actress looked more than worthy of her role in the film as Princess Tamina.
Of course it wasn’t just the British beauty causing a stir at the event, which took place in London's Westfield shopping centre - transformed to look like a Persian city in honour of the screening.
Proving very popular on the night was handsome American actor Jake Gyllenhaal, who takes the lead in the action adventure.
Twenty-nine-year-old Jake underwent a tough training regime to play the hero, Prince Dastan, and his impressive shape has already become a talking point of the film.
But all the focus on his physique has come as a shock to the Donnie Darko star, who admitted: "I don’t think I ever expected that much attention."
"I think it was more like I tried to train to be able to look like I was, the character in the video game, and that I was able to do the stunts that were asked of me."
It's not a fact lost on Gemma, who described the handsome Hollywood star as "so gorgeous."
"When they told me he was my co-star, I had to pinch myself," she admitted.
Speaking at the premiere, director Mike Newell said he was delighted with both his leads, who pulled out all the stops for the film.
"Jake was terrific. He worked so hard to make himself Dastan," he said. "Gemma was adorable. When I first started working with her, she was 21 and three months out of drama school."
Loosely based on a video game, Prince of Persia: The Sands of Time also stars fellow English actors Sir Ben Kingsley and Alfred Molina.
It hits screens in the UK on May 28.