Katie was looking in good health following her recent mystery illness and she cradled Jett close to her chest while keeping him warm in a cosy blanket.
Princess, six, was beaming and looked cute in a pink gillet, matching woolly hat and frilly tutu skirt as she sat next to her mum and baby brother in the back of a taxi.
Although 35-year-old Katie was wearing minimal make-up, she looked relaxed and fresh-faced for her evening out in London.
Proving her yummy mummy credentials, she was dressed in over-the-knee leather boots and kept her highlighted hair straight and loose.
The star and her two children visited the exclusive Novikov restaurant for a meal with pals before heading off for a spot of late night shopping.
Keeping it real, Katie and Princess were seen hunting for some last minute bargains at a designer boutique and in department store Selfridges.
The mum-of-four, who also has two sons - Harvey and Junior, kept four-month-old Jett snug in his pushchair as they pounded the pavements.
Earlier this week, Princess became a big sister for the second time when her dad Peter Andre and his girlfriend Emily MacDonagh welcomed a baby girl into the world.