And he knows exactly what she's getting herself in to after taking part in the 2010 series - and winning it!
After Katie entered the CBB house on Friday night (16 January) in a shock twist, man mountain Alex took to Twitter to wish her all the best... Well, we weren't expecting that!
Alex wrote: "Good luck @MissKatiePrice Go win! X"
Although the couple divorced acrimoniously in 2011, it seems Alex has no hard feelings towards his former glamour model wife.
Alex, now 39, became Katie's second husband when they got hitched in Las Vegas in 2010, but the marriage lasted less than a year.
Good luck @MissKatiePrice— Alex Reid (@AlexReid) January 16, 2015
Go win! X
And Alex wasn't the only famous name to react to Katie joining the likes of Perez Hilton and Katie Hopkins in the house.
Silver fox Phillip Schofield tweeted: "Now THIS is going to set a volatile house ON FIRE!! Pahahaha #CBB bloody love it @MissKatiePrice."
Former TOWIE star Lucy Mecklenburgh said: "Katie Price in #CBB! Will Perez get jealous? He thought he was a producers dream! What about Katie!"
While the winner of last year's Big Brother Helen Wood added: "Aww I hope @MissKatiePrice @KTHopkins & @michellevisage all become bezzys! @bbuk #CBB."
Mmmmm, we're not sure about that!
See the other celebs who posted comments about Katie Price in CBB:
TOWIE's Ferne McCann: "Catching up on #CBB this is such a great house. Feel like fast forwarding to @MissKatiePrice entrance can't cope #epic."
Former TOWIE star Billi Mucklow: "So excited about #KatiePrice going in #CBB it's going to go off in that house."
CBB winner Charlotte Crosby: "Got to say even tho I'm having an amazing time I am DEVO im missing Big brother!!! @MissKatiePrice is in! She's gunna rock it!!! Heart Her!"
TOWIE's Bobby Norris: "I think @MissKatiePrice could win this #CBB."
Geordie Shore's Daniel Thomas: "Am buzzing @MissKatiePrice has gone in the #CBB house a think she's puree wkddddd."
Former TOWIE star Cara Kilbey: "Can't wait to watch Katie Price in this house... #CBB."
Made In Chelsea's Lucy Watson: "Pretty excited about this @MissKatiePrice."
Former CBB star Casey Batchelor: "Yesssssss! @MissKatiePrice Go on Katie! Can't wait to watch her in the house! Whoop! #CBB."
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