The radio presenter, 34, met the professional dancer, 29, while taking part in the BBC series in 2017, when she was partnered with Aljaz Skorjanec.
The couple confirmed their relationship shortly after the series finished and welcomed their first child, Mia, earlier this year.
Social media star Joe Sugg will also team up with his girlfriend Dianne Sugg after the pair reached the final last year.
Debbie McGee, who appeared on the show alongside Atkinson in 2017, will dance with 2018 winner Kevin Clifton, while Good Morning Britain’s Richard Arnold will perform with Luba Mushtuk.
Mark Wright, who competed in 2014 alongside Karen Hauer will be paired up with Janette Manrara.
Professional Graziano Di Prima, who made his debut on the show last year, will dance with Chizzy Akudolu.
Each couple will perform a festive routine in a bid to be crowned Christmas champions.
Atkinson said: “I had the absolute best time on Strictly and it completely changed my life, so I am absolutely overjoyed to be returning to the dancefloor this Christmas with a new challenge, and of course to be back with the gang.”
The festive special will be hosted by Tess Daly and Claudia Winkleman, with judges Shirley Ballas, Motsi Mabuse, Bruno Tonioli and Craig Revel Horwood also taking part.
The Strictly Come Dancing Christmas special airs on BBC One on Christmas Day.