The 55-year-old GMB host took to Twitter on Thursday to take a swipe at the BBC Breakfast programme editor, Richard Frediani.
Frediani formerly worked as the head of news at ITV, before landing a gig on the rival network last year, coordinating the breakfast news show.
Clearly happy with his work on the BBC, he shared a series of photos from behind-the-scenes on set with his Twitter followers, claiming BBC Breakfast was "dominating" early-morning viewing across the country.
He said: "Another day of @BBCBreakfast dominating morning TV.
"More viewers throughout the key 8am hour.
"A peak audience at 44.4% and 2.13 million – nearly a million ahead of any other show.
"#mostwatched #No1 #massive."
Having spotted the proud tweet, Piers couldn't help but snap back, asking Frediani to prove BBC Breakfast's worth with facts and figures.
He wrote: "Hi mate, given you joined them a year ago, do you have the comparative year-on-year numbers for both shows for this week, so everyone can see the magical Frediani effect on ratings?"
Adding the hashtag "awks" and a winking-emoji, Piers made it clear the biting remark was intended to sting.
Piers' rivalry with BBC Breakfast has a rich history, with the ITV star having locked horns with presenter Dan Walker in the past.
Their war of words erupted during the lockdown, when Piers criticised Dan's interviewing technique as a variety of politicians appeared on the bright red BBC sofas.
Suggesting the Brit government were boycotting GMB in June, Piers claimed the 43-year-old was landing the political interviews "because he won't jump in" with questions about Covid testing figures.
Dan snapped back: "It is essential that politicians are allowed to speak. The idea (from some) that we, and others, don't challenge ministers is completely untrue.
"Important to ask questions. Important to press. Important to let you listen.
"Thanks for watching."
Piers was quick to issue his own fierce response, saying: "No mate, you blew it, you had a chance.
"The health secretary gave you a load of flannel about why the number of people being tested is meaningless, and you should have torn him to ribbons.
"That's your job. It's not to sit back and let him spout complete nonsense."
He finished: "Next time, jump in, and don't let him get away with it. I can't do it, because he boycotts us. Come on Dan, get a grip son."