Lorraine Kelly criticised Jennifer Arcuri live on air, asking "what's the point of you coming on TV?" after the US businesswoman appeared to dodge questions on Good Morning Britain.
Ms Arcuri swerved queries about her relationship with Boris Johnson, telling hosts Piers Morgan and Susanna Reid that she did not want to "be pressured into admitting" to anything about her links to the Prime Minister.
During a live link-up following the interview, Kelly told Morgan and Reid: "That was crazy wasn't it? What's the point, coming on and not answering any questions?"
— Good Morning Britain (@GMB) November 18, 2019
Morgan asked Ms Arcuri if she had a response to Kelly, who repeated directly to her: "It just doesn't make any sense. What's the point in you coming on and not saying anything?"
Seemingly taken aback, Ms Arcuri asked: "I'm sorry?"
Kelly said: "What is the point of you coming on TV to clear the air and then you don't say anything?"
Ms Arcuri replied: "I believe I said a few things. What is it that you're looking for that I should say?"
Kelly responded: "You didn't answer any of the questions that were put to you, and I just don't see the point of you coming on to be honest."
Ms Arcuri has been at the centre of a controversy involving Mr Johnson, and in an interview with ITV Exposure that aired on Sunday she said she wished she had declared their personal relationship as a potential conflict of interest to avoid her "humiliation".
Ms Arcuri claimed Mr Johnson cast her aside as though she was a "gremlin" after she tried to contact him for advice on how to handle the media interest.
Her links with Mr Johnson came under public scrutiny earlier this year over allegations she received favourable treatment for her business ventures during his eight-year stint as mayor of London.
The show alleges the pair were involved in an affair for more than four years.
In the interview with Good Morning Britain on Monday, Ms Arcuri was asked if she had had an affair with Mr Johnson after using the word in the documentary.
She said: "I'm not going to answer that question, but as you can tell, there was a very special relationship there.
"When it did come out, half the people already assumed the affair and told me to admit it. The other half wanted me to deny, deny, deny."
She added that she can "concede to the fact that I have been heartbroken".