Laura Kuenssberg, the BBC's former political editor and now the host of its flagship Sunday morning news program, said she mistakenly sent Johnson the notes "in a message meant for my team" and this meant the interview had to be cancelled.
"It's very frustrating, and there's no point pretending it's anything other than embarrassing and disappointing, as there are plenty of important questions to be asked," Kuenssberg said on X.
While prepping to interview Boris Johnson tomorrow, by mistake I sent our briefing notes to him in a message meant for my team. That obviously means it's not right for the interview to go ahead. It's very frustrating, and there's no point pretending it's anything other than…— Laura Kuenssberg (@bbclaurak) October 2, 2024
"But red faces aside, honesty is the best policy."
As a publicly owned broadcaster, the BBC comes under huge scrutiny as to how it holds politicians to account, with leading political correspondents often accused on social media of favouring one party over the other.
The interview was due to be broadcast on Thursday evening and had been advertised as Johnson's first major TV interview to promote his memoirs.
Johnson was expected to discuss his government's handling of the COVID-19 pandemic and the parties in Downing Street that contributed to the end of his premiership.
Johnson, who was prime minister from 2019 to 2022, will have his memoir, Unleashed, published on October 10.
A BBC spokesperson said the mistake made the interview "untenable" and the broadcaster and Johnson's team had agreed to cancel it.