The H&M Divided Party will see the brand officially launch its #HMLovesMusic campaign, of which Foxes is the face.
Foxes worked with the retailer to shoot key pieces from its Autumn 2015 Divided Collection in Los Angeles, which will launch in the UK and Ireland on 23 July.
H&M is running an online competition where fans can enter a draw to win one of 20 exclusive tickets to the launch party by answering a series of Foxes-related questions.
Pernilla Wohlfahrt, head of design at H&M, said: "Foxes has the perfect style for this campaign – her effortless look is so inspiring. It’s all about a mix of fun pieces that can be worn together in so many different ways."
Specific details of the event will be revealed closer to the date.