It will be Brook's third Strictly appearance, after she danced in the 2007 series and the 2008 Christmas special.
The 33-year-old tweeted: "Excited to get back in the rehearsal Studio this week for @bbcstrictly Christmas Special! #Glitterballs."
Brook finished her stint in the burlesque show Crazy Horse on Friday (November 23), just in time to celebrate her 33rd birthday.
Also due to appear in the festive special is newsreader Kaplinsky, who won the first ever series in 2004, and singer Rachel Stevens.
Gill and former footballer Muamba, who suffered a near-fatal cardiac arrest on the pitch eight months ago, are the only beginners in the Christmas show.
Strictly's 2009 winner Chris Hollins, last year's runner-up Chelsee Healey and sprinter Colin Jackson will also appear.
Photo gallery - Strictly Come Dancing 2012 week seven results show: