The flame-haired Duchess was joined by socialite Heather Kerzner for dinner and drinks at upscale Scott's restaurant in Mayfair.
The women held hands as they exited the establishment.
Fergie, 59, looked relaxed and smiled for photographers as she sat into a waiting car.
She appeared to go makeup free for her evening on the town and added a touch of sparkle with dainty gold hoop earrings and a matching pendant.
Fergie, who shares daughters Princess Beatrice and Princess Eugenie with ex-husband Prince Andrew, has made a return to the social scene in recent months after being unofficially welcomed back into the royal fold after Eugenie's October wedding to Jack Brooksbank.
The wild and wonderful Duchess is widely rumoured to be back together with the son of Queen Elizabeth, with the two reportedly sharing a home again.
Fergie once famously referred to their situation as being "the happiest divorced couple in the world".
WATCH this video for all the details on Fergie and Andrew's rekindled romance!