The former newsreader and BBC Radio 3 presenter lifted the Christmas Trophy after returning to the ballroom two years after she reached the final.
Partnered with Brendan Cole, the pair impressed the judges with their routine to Viennese Waltz to ‘White Christmas’ by Otis Redding, scoring 37 points out of a possible 40.
The couple, who reached the final together in 2012, picked up 39 points from the judges for their Jive to ‘Run Run Rudolph’ by Kelly Clarkson.
The winner was decided after the judges’ scores were combined with the vote from the studio audience, compared to the usual viewer vote, given the show was pre-recorded.
Katie was clearly shocked to have won the special, and told hosts Tess Daly and Claudia Winkleman: “Oh my goodness, I’m so stunned! I thought any of these gorgeous people were going to win, not us. This is brilliant. It feels fantastic, it really does!”
The festive edition also proved to be extra special for - how do we put this? - less gifted dancers Judy Murray and Jeremy Vine, who both received their highest scores ever (31/40) for their Christmas routines.
However, something tells us the judges were feeling in a generous mood as they dished out a number of eights for both routines.
There was also a musical performance from the Kaiser Chiefs as well as a spectacular group number, set to Elton John’s hit ‘Step Into Christmas’.
‘Strictly Come Dancing’ returns to BBC One in the autumn.