Ross McEwan has resigned as the chief executive and executive director of Royal Bank of Scotland.
The banking group, which recently returned to profit for the first time in a decade, revealed Mr McEwan has a 12 month notice period.
He will remain in his position until a successor has been appointed but the date of his departure will be confirmed in due course.
Mr McEwan said: "After over five and a half very rewarding years, and with the bank in a much stronger financial position it is time for me to step down as chief executive. It has been a privilege to lead this great bank and to have worked with some really outstanding people in the process.
"It is never easy to leave somewhere like RBS. However, with much of the restructuring done and the bank on a strong and profitable footing, I have delivered the strategy that I set out in 2013 and now feels like the right time for me to step aside and for a new chief executive to lead the bank.
"I'd like to thank the board, shareholders and UKGI for the support they have shown me during my time at the bank and our colleagues for the remarkable job in turning this bank around."
RBS is still majority-owned by the British government, which holds a 62 per cent stake in the business after it injected £45.5bn into the bank at the height of the financial crisis to maintain stability.
In 2015 the government began the process of gradually selling its stake, which has fallen from a peak of 71 per cent and last year RBS posted its first annual profit for 10 years, making £752m.
Howard Davies, RBS's chairman, said: "Ross has worked tirelessly to make the bank stronger and safer and played the central role in delivering a return to profitability and dividend payments to shareholders.
"The board and I are grateful for the huge contribution Ross has made in one of the toughest jobs in banking. His successful execution of the strategy to refocus the bank back on its core markets here in the UK and Ireland has helped to deliver one of the biggest UK corporate turnarounds in history.
"RBS is now well positioned to succeed in the future in what is a rapidly evolving landscape for the banking sector. We will be conducting an internal and external search for his successor, which will start immediately."