Northern Rock announced the departure of chairman Matt Ridley and said the "time was right" to accept his resignation.
Dr Ridley leaves Northern Rock a month after the mortgage lender's liquidity crisis and the subsequent run on the bank.
He will be replaced by Bryan Sanderson, former chairman of Bupa and of Standard Chartered bank.
The news comes just days after MPs launched a scathing attack on Dr Ridley in a Treasury Select Committee hearing, demanding to know why he was "clinging to office" as head of the group that caused the first bank run in nearly 150 years.
Northern Rock said that Dr Ridley had offered to resign in September as the crisis unfolded, but was asked to remain in place until new financing had been secured and after he had represented the group at the Committee grilling.
The group said: "He and the board now believe that the time is right to accept his resignation as a director and chairman of the company."
Dr Ridley will remain in place until his replacement, Mr Sanderson, gains relevant approvals from City watchdog the Financial Services Authority.
Dr Ridley, who received a salary of £300,000 last year, leaves Northern Rock after nearly three-and-a-half years in the role.
He first joined the group's board in 1994.
His father, Viscount Ridley, was also formerly chairman of Northern Rock, when the group was a building society.
