The Breakfast presenter, who is on maternity leave, taunted the prime minister just seconds after she passed him on stage while hosting the Convention of the North in Rotherham, South Yorkshire.
She took Mr Johnson to task for referring to former PM David Cameron as a ‘girly swot’ in a private Cabinet paper.
After she encouraged the crowd to applaud Mr Johnson, she said: ‘I’d just like to point out I am a girly swot and I’m proud of it.
‘Let’s see who’s in the job the longest.’
Steph McGovern for PM pic.twitter.com/Nr1PVu1frm
— Abdi Duale (@AbdiDuale_) September 13, 2019
The comments came days after Mr Johnson used similar language in the Commons, calling Jeremy Corbyn a ‘big girl’s blouse’ over the Labour leader’s decision not to back the PM’s bid for an election while the risk of a no-deal Brexit remained.
Writing on Twitter on Friday afternoon, McGovern sad: ‘At a non BBC event I was hosting today, I made a light hearted remark after the Prime Minister’s speech.
‘Sorry that this caused offence to some. That was absolutely not my intention.’
Mr Johnson also used the ‘girly swot’ phrase against Mr Cameron in a 2013 interview to dismiss the former Conservative Party leader for getting a first class degree at Oxford – a grade higher than the PM.
Last week, Labour’s Yvette Cooper criticised Mr Johnson for his use of language.
She tweeted: ‘The Prime Minister of Great Britain thinks he’s still back at Eton, “girly swot” “big girl’s blouse”, – what century is he in if the word “girl” is one of his staple insults?’
Dawn Butler, Labour’s shadow women and equalities minister, said: ‘With a Prime Minister like Boris Johnson, what hope is there for the advancement of women’s rights?’
The BBC declined to comment on the remarks made by McGovern, but said she is allowed to carry out external engagements when on maternity leave
Boris has faced a number of hecklers and angry members of the public in person in recent weeks.
At the same event in South Yorkshire, a man was dragged out of the building after urging Boris to ‘get back to Parliament’.
In Doncaster this afternoon, the Prime Minister was confronted by another furious voter.
The unnamed woman said: ‘People have died because of austerity.
‘And you’ve got the cheek to come here and tell us austerity is over and it’s all good now and we’re going to leave the EU and everything’s going to be great – it’s just a fairytale.’