The duo appear in an advert for the event, appearing in a studio urging fans to get involved in the event which aims to revive the fortunes of the fashion industry in the struggle economic climate.
"Meet designed and models - and who doesn't want to meet models, right?" asks Bieber in the advert for the 6 September event, which sees special events and late night store openings across the planet.
"You should totally come!" Says Taylor Swift, to which Justin Bieber replies: "I will definitely be there. You bring your friends, i'll bring my friends, we can all hang out."
Justin Bieber recently risked the wrath of the entire UK when he questioned why Prince Williams didn't use drugs to grow his thinning hair back, while Taylor Swift has broken download record with her new single 'We Are Never Ever Getting Back Together'.
Watch the promotional video below: