The multi-Grammy award winner will be in town to promote her new album Memoirs Of An Imperfect Angel, out later this month.
Westfield's Southern Terrace will be decked out with a VIP pink carpet on which Mariah will make an entrance under a snowfall of butterfly confetti.
The venue is expecting more than 2,500 people to attend the switch on, which is scheduled for 6pm.
"Mariah Carey switching on the lights will be the icing on the cake for what has been an incredible year for Westfield London," said the venue's head of events Joe Russell.
"We've had lots of celebrities come to Westfield in the last year, but Mariah is the biggest," he added.
From this Saturday (14 November) shoppers will be able to experience the centre's festive offering, Wonderland, incorporating a kids 3D Santa’s Wish Kingdom grotto and Adult Grotto.
The West London shopping centre
Then, last week, it hosted the
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