The supermarket is rolling out the initiative as an extension of its 'Christmas school of magic' TV campaign.
Smith will show users how to cook their Christmas turkey and decorate cakes, in videos that will appear on YouTube. Meanwhile, weekly live Q&A sessions featuring culinary experts, including Masterchef 2010 winner Dhruv Baker, will be hosted on Facebook.
The first video shows Waitrose cookery-school chef Gordon McDermott advising consumers on preparing for Christmas. The clip will air on Wednesday (30 November) on Facebook. It is also launching a Christmas day planner app.
Waitrose digital communications senior manager Julie Randall said the supermarket's success over the next few weeks 'depends on the way we inspire customers for the big day'.
Digital activity has been created by social-media agency Manning Gottlieb OMD, after it won Waitrose's account in the summer following a competitive pitch process.
Rival supermarket Tesco is also investing heavily in social media and is employing eight qualified chefs to troubleshoot customer's cooking problems on Christmas day.