Kate Garraway and Richard Madeley apologised to viewers after John Simpson swore live on Friday's edition of Good Morning Britain.
The veteran foreign correspondent was being interviewed on the ITV breakfast show at around 0650 BST.
Discussing his recent novel, the 76-year-old recalled his experience of a mock execution while working in Beirut.
After Simpson used an offensive word, Madeley said: "Obviously we apologise to anyone who was offended."
Simpson had been explaining that about 80% of the events featured in his novel had either happened to him or people close to him during their careers as foreign correspondents, adding that the protagonist both "is me and it isn't".
Good Morning Britain tweeted a clip of the interview, although not the section which featured the offending word.
'I can't believe this is how it ends.'— Good Morning Britain (@GMB) July 23, 2021
Legendary broadcaster John Simpson was victim to a mock execution in Beirut and he describes what he thought were his last moments. pic.twitter.com/G71eWehCJu
After Madeley asked whether a mock execution detailed in the book was based on real life, Simpson said: "It was me in Beirut some years ago and I was made to kneel down.
"A guy stuck a gun in the back of my neck and pulled the trigger and I thought my last moment had come.
"And then everybody laughed and I got up and I brushed off my knees and I thought, 'I've got to reassert myself here'.
"So I said to the guy who had fired the gun, or hadn't fired the gun, 'Do you know what? You're a real [expletive]'."
Simpson held his hands up then covered his mouth after realising his mistake, and immediately apologised.
Garraway joked he was "also in trouble now for saying that on breakfast television".
She added: "We won't give you a mock execution. You are OK John, you are OK." She also apologised to viewers.
Madeley is one of several guest presenters who has been drafted in to present the show following Piers Morgan's departure in March.
A permanent replacement for Morgan has not yet been announced.
Simpson has been a well-known foreign correspondent for the BBC for decades, after first joining the corporation in 1970.
He has interviewed world leaders and reported from more than 120 countries, including 30 war zones.