The campaign will be created by ad agency Grey London, which picked up the account last year.
It will be timely for the launch of the second Paddington film, which is due to be released in UK cinemas on 10 November.
The adorable bear will be a shift away from previous M&S Christmas campaigns, which were created by Y&R London.
Last year’s ad made Mrs Claus the centre of attention, and the retailer said at the time that it was its most "customer-centric" campaign to date (see video below).
It will not be the first time a Christmas campaign will feature an animated bear; last year Heathrow and Havas London created a ad with two bears.
Havas is currently promoting the new Paddington film with large book installations around London.
An M&S spokeswoman said: "We’d never reveal the story of our Christmas ad ahead of the campaign launch; you’ll just have to wait and see what we have in store for customers this year."
A version of this article first appeared on PRWeek sister title Campaign.