The retailer is running a teaser clip of Rosie Huntington-Whiteley chasing after a Scottie dog, before falling down an 'Alice in Wonderland'-style hole, on its Facebook page and via a promoted tweet on its official Twitter account.
Marks & Spencer will feature the full two-minute ad on its Facebook page 48 hours before it launches on TV next Wednesday November 6
The move is a first for the retailer, which previously did not trail its Christmas ad on social media before airing it on television.
The strategy follows in the footsteps of rival John Lewis, who, in recent years, has previewed its high-profile Christmas ads on social media a day before the TV ad launch.
Creative by Rainey Kelly Campbell Roalfe/Y&R also features supermodel David Gandy in the role of Huntington-Whiteley’s love interest.
Bonham-Carter stars as a wizard in homage to T'he Wizard of Oz' and the ad marks her first ever advertising role.
Patrick Bousquet-Chavanne, executive director of marketing and business development at M&S, said: "With this year’s ad we wanted to recapture the magical essence of Christmas that our customers tell us is synonymous with M&S."
There are only two versions of the two-minute long version of the ad, with the second due to air on Sunday 10 November on ITV during 'Downton Abbey'.
The 'Downton Abbey' ad will reveal the name of the dog in the ad after a social media campaign that asks people to vote on whether the dog should be called Magic or Sparkle.