Balmain creative director Olivier Rousteing debuted his much-anticipated collection with Swedish retailer H&M on Tuesday night (20Oct15), with models such as Alessandra Ambrosio, Karlie Kloss, Kendall Jenner, Gigi Hadid and Jourdan Dunn showing off his designs on the catwalk for the first time.

But after the entire line was presented, attendees were treated to a surprise performance by the veteran pop stars, as they took to the stage decked out in tailor-made Balmain for H&M gear.

The Backstreet Boys performed a short set, featuring their hits Larger Than Life, I Want It That Way and Everybody (Backstreet's Back), and brought Rousteing back on the stage to praise him for his collection.

Among those who watched the star-studded fashion show were singer Ne-Yo, racer Lewis Hamilton, Brit Alexa Chung, models Alek Wek and Coco Rocha, singer Ellie Goulding, actress Rosie Huntington-Whiteley, and Jenner's younger sister Kylie Jenner.

The one-off concert is a welcome reprieve for singer Nick Carter, who is currently competing in U.S. competition show Dancing with the Stars. Just the night before (19Oct15) he scored a nearly perfect score for his rendition of John Travolta's iconic disco dance in his hit 1977 film, Saturday Night Fever.