They were joined on the red carpet in sunny Los Angeles by stars including Katy Perry, Taylor Swift, Miley Cyrus and Rihanna, who showed off her newly-cropped hair.
Take a look through our gallery below for some of the red carpet highlights:
Looking gorgeous in all-white, Vanessa, Mollie, Frankie, Una and Rochelle proudly flew the flag for British music.
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Copyright: Everett Collection/Rex Features
Who do you think was best dressed on the red carpet? Don't forget each week we'll be giving £50 to the person who writes the Comment of the Week!
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