The former Apprentice star is known for blasting her fellow celebs and this weekend, Stereo Kicks were at the receiving end.
But, following their exit from the show, band member Tom Mann couldn't resist hitting back at Katie and her latest claims.
During Sunday night's results show, Stereo Kicks were the latest act to leave The X Factor after receiving the fewest public votes.
And, on hearing about the boys' departure, Katie embarked on a Twitter tirade against the eight piece.
After first tweeting her delight at the band being given the boot, the 39-year-old then went on to say: "Stereosh*** wishing they had spent a bit of time at school instead of practicing with a hairbrush in the mirror. Burger King kick. NEET kick."
Throughout the show, Katie has been known to criticise the boyband and fed up with her harsh comments, Stereo Kicks' Tom finally hit back.
He replied: "I got 3 A*s and a B at A Level. You n*b. - Tom."
Following his Twitter spat with Katie, Tom told Yahoo! Celebrity he couldn't help but reply as her comments over the weeks have been "needless".
He said: "She's sent quite a few mean tweets and the reply was not out of bitterness on our part...
"Usually we would leave that sort of stuff but, if she's going to do it, we'll come back having a bit of a laugh."
Like Tom, James Graham agreed that Katie's criticism has been unnecessary and needs to stop.
"She's been doing it every week and it's just like 'shut up,'" James said. "We despise her."
The boys' fallout with the TV personality comes after they lost their place in this year's competition.
Speaking to Reveal after their exit, Stereo Kicks told us Louis Walsh had broken down in tears following Sunday night's result.
Joined in the bottom two by Cheryl Fernandez-Versini's last girl Lauren Platt, the boys were sent home after Simon Cowell decided to take the vote to deadlock.
But, despite their X Factor departure, Stereo Kicks insisted they would be staying together as a group as they hope to land a record deal.
Promising fans this won't be the last of the boyband, Chris Leonard said: "We're not going anywhere. So far it's been amazing for us.
"We're going to stick around and do our best to come back bigger and stronger from this."
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Watch Stereo Kicks perform 'Run' here: