The 23-year-old was praised for her "personal rock-chick style" and daring red carpet looks, despite regularly sporting scruffy off-duty clothes in the poll by Britain's Glamour magazine.
KStew has joked in the past: "I go outside, and I'm wearing a funky T-shirt and my hair is dirty, and people say, 'What's wrong with her? She needs to invest in a hairbrush'."
Harry Potter actress Emma, 23, held on to second place once again. The starlet has made a name for herself in recent years by ditching her schoolgirl persona and embracing a pixie crop and adventurous
It comes as no surprise the Duchess of Cambridge rounded out the top three, gaining one place from last year.
The royal beauty is admired worldwide for her sophisticated and demure outfit choices, and has an unprecedented power to sell out high street garments.
The Amazing Spider-Man star Emma Stone and country singer Taylor Swift placed fourth and fifth respectively, with Keira Knightley, Kate Moss and Duchess Catherine's sister Pippa Middleton all ranking in the top 50.
The style victory for Kristen is a welcome change after the actress was voted second most hated celebrity in Star magazine's annual poll last month, with Gwyneth Paltrow narrowly beating her to the crown.
Kristen also picked up the unflattering accolade of least sexy actress in Hollywood earlier this year.