Richard Sharp says he will not stand down as chairman of the BBC over the Boris Johnson loan row.
He told the BBC he was confident he would be cleared by a government watchdog probe into his appointment.
Mr Sharp is under scrutiny over his links to the former prime minister and his role in talks over an £800,000 loan.
He said he was confident he was “appointed on merit” and welcomed a review.
Speaking to the BBC, he said he “absolutely” feels comfortable about being the face of BBC impartiality, a fundamental part of how the organisation is expected to operate, despite questions which have emerged this week.
He rejected suggestions he should stand down pending the findings of an investigation by William Shawcross, the Commissioner for Public Appointments.
Mr Sharp said he welcomed that scrutiny and had taken steps to ensure “due process was followed by the book”.
He said he did that by contacting the Cabinet Secretary Simon Case to discuss an offer of financial assistance being made for the then PM.
That came from Sam Blyth, a multimillionaire who Mr Sharp described as an “old friend” and who is also a distant cousin of Mr Johnson.
Mr Blyth had offered to be the guarantor on a loan for Mr Johnson after reading press reports that he was under financial pressure.
Mr Sharp was involved in discussions in December 2020, a few weeks before being announced as the government’s choice for the senior BBC role.
He maintained that Mr Johnson’s personal finances were not discussed when he met with him and Mr Blyth in May 2021, four months after he had been confirmed as the government’s choice for the BBC role.
Asked how that meeting came about, he said Mr Blyth had called him to say he was “having dinner with [Mr Johnson]” at Chequers.
“I said, ‘yeah great’, I’d never been to Chequers. I drove down… and I used that opportunity to bat for the BBC”, Mr Sharp said.
He said the loan arrangement did not come up and insisted that he doesn’t “know anything” about Mr Johnson’s personal finances.
Mr Sharp said he made the cabinet secretary aware of his application to be chairman when he told him about Mr Blyth’s financial offer in late 2020.
He agreed with Mr Case that he should play no further part in any loan guarantee talks. He said this was the last involvement he had in the matter.
Mr Johnson was also advised by the Cabinet Office not to further discuss finances with Mr Sharp.
Asked why he agreed to approach the cabinet secretary on behalf of Mr Blyth, Mr Sharp said he had access while working as an economic adviser during the pandemic.
He added: “With the benefit of hindsight, particularly at that time, I might have said ‘do it yourself’ but I was working in Downing Street at the time…”.
He said he arranged an appointment with Mr Case and notified Mr Johnson “as a courtesy and explained why” he was meeting the cabinet secretary, to which the then PM “acquiesced”.
In a statement to The Sunday Times, a spokesman for Mr Johnson said they had known each other “for almost 20 years”. He acted as an advisor to Mr Johnson during his time as London mayor.
Mr Sharp was also reportedly close to Rishi Sunak when the pair worked together at Goldman Sachs prior to his election to Parliament.
He was brought into the Treasury to advise on support for businesses during the pandemic while Mr Sunak was Chancellor.
The appointment of the BBC chairman is a political decision ultimately signed off by the prime minister with input from the culture secretary and a panel.
The chairman is responsible for “upholding and protecting the independence of the BBC” and ensuring it is fulfilling its core responsibilities.
It is separate from the role of director general, who acts as its editor-in-chief with responsibility for its output and workforce.
Professor Diane Coyle, who served as acting chair of the BBC Trust in 2014, said she applied for the role of chair at the same time as Mr Sharp but was not shortlisted and received “no explanation”.
She told BBC Radio 4’s Today programme that Mr Sharp had shown “poor judgement” by getting involved in the loan talks and that it would damage the ability of BBC journalists to do their jobs, particuarly those working overseas.
On Monday Downing Street rejected allegations of “cronyism” and Mr Sunak described the appointment process as “rigorous” and “transparent”.
Labour leader Sir Keir Starmer said there were “clearly serious questions to answer”.