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The stunning Spanish siren stolled the blue carpet – which represented the sea – in a white embroidered Givenchy gown, featuring zip detailing on the front and sides.
Completing the look was a gold clutch, and poker straight hair.
The 37-year-old actress revealed she was so keen to work on the film that she accepted the role without having read the script.
"It was a big honour to feel invited," she said. "I loved the other three (films) and I love what Johnny has created."
The brunette beauty, who was pregnant while she filmed the swashbuckling adventure, plays lady pirate Angelica, the daughter of Blackbeard – who is portrayed by Ian McShane.
Her character is also an old flame of Captain Jack Sparrow – Johnny's infamous alter ego.
The man himself was greeted by cheers and excited screams from the crowd as he turned up to the premiere, which was held in Westfield shopping centre in Shepherd's Bush.
The 47-year-old star – dapper in a charcoal suit and teal shirt – had nothing but praise for his leading lady.
"I've worked with her twice now, and it's always been a real pleasure," he said. "She's very special, very talented, and also at the same time as an actress she gives you so much that you weren't necessarily expecting, so you're up on your toes."
He hopes to continue with the hugely-successful franchise, saying: "There's a lot more I feel I can do with these films. There are a lot more possibilities to be mined."
Pressed on whether the franchise will continue with a fifth film, he said: "I don't know what the situation with five will be, but I do know that we're talking about it."
As well as an assortment of UK celebs – including presenter Lizzie Cundy and Lady Victoria Hervey, there was one very special young guest.
Nine-year-old school girl Beatrice Delap (above left) was reunited with Johnny after first meeting him when he paid a surprise visit to her school.
The actor, who was filming in South-East London, dropped by Beatrice's Greenwich school in character as Jack Sparrow after she wrote to him asking for help to stage a mutiny.