The Specialist Schools and Academies Trust said that comments by Des Smith, the head of All Saints Roman Catholic secondary school, in Dagenham, "were without any basis in fact".
Its strongly-worded statement insisted "beyond any doubt" that no member of its governing council had ever made such a promise.
Mr Smith resigned from the trust's council in January after allegedly being taped telling an undercover reporter from the Sunday Times that anyone sponsoring an academy may be offered a knighthood or peerage. The 60-year-old was questioned earlier this month by detectives investigating the claims.
The trust agreed to release a statement - copied to police - following its latest council meeting on Monday to clarify its position. It said Mr Smith's involvement with the trust was "limited solely to educational matters" and that he had worked as a consultant providing advice to two academies. He also acted in a similar consultancy role with the Department for Education and Skills, the statement said.
It added that Mr Smith was invited to join the council in November 2005, in recognition of his record as a head, but "at no time did he have any involvement whatsoever in fundraising or the seeking of sponsorship for academies".
The trust said: "We believe it a great pity that his career as an outstanding headteacher might have been harmed by this episode."