The girl group, who are on course to top the UK charts with their debut single 'Cannonball', attended the Glamour magazine event, held in honour of Contostavlos's recent cover issue.
Bunton had previously given the group her backing, tweeting: "So excited for Little Mix - get ready for the ride, girls!!"
The foursome - Jade Thirlwall, Perrie Edwards, Leigh-Anne Pinnock and Jesy Nelson - posed alongside the singer-turned-TV judge, who later told her Twitter followers: "So lovely to see Little Mix, its all just starting for them! Such sweethearts!!!!"
Writing on their official Twitter page this morning, Little Mix said: "Went for dinner last nite with tulisa n glamour magazine was amazing! Also met Emma bunton wat an inspiration!"
The Kensington Roof Gardens bash came the night after the X Factor series wrap party, at which axed finalist Frankie Cocozza was involved in a scuffle with paparazzi.
> Simon Cowell wants 'X Factor' Little Mix to be new Spice Girls
Watch Digital Spy's chat with Little Mix below: