The 30-year-old will be picking her favourite pieces from the brand's autumn/winter 2014 ready-to-wear collection on a month-by-month basis until January, revealing her selection on the American label's website.
Alexa Chung has been revealed as a guest editor for Tommy Hilfiger
"Alexa is the true definition of an 'It' girl," Tommy told WWD. "She's cool, witty, smart and has a great sense of style. She knows how to mix of-the-moment styling with classic design for a unique look that's totally her own."
"To be embraced by such a behemoth of an American fashion brand is a huge honour," added Alexa.
The gorgeous brunette has already revealed her autumn must-haves for October, pairing a black A-line skirt with a cowl-neck sweater and some black leather leggings. To complete the look, Alexa added an oversized wool-blend cocoon coat in a gray plaid pattern.
Alexa Chung took over the brand's Instagram account during New York Fashion Week
It's not the first time this year that the British style icon has teamed up with the designer. During New York Fashion Week in September, Alexa took over the brand's Instagram account giving fans a sneak peek behind-the-scenes at the show, as well as what she was up to.
The fashionista also made waves during London Fashion Week on the front row at Topshop Unique where she charmed the fashion pack with her dressed down yet chic outfit.
Teaming a yellow top with a leopard print miniskirt, Alexa completed her look with a quirky pale pink Chanel handbag in the shape of a milk carton.
For more details of Alexa's winter must-haves head to tommy.com/alexachung.