Andy Hunt has resigned as chief executive of the British Olympic Association (BOA).
He told a BOA board of directors meeting today that he would leave at the end of this month to pursue other opportunities.
Mr Hunt, who helped manage Team GB as chef de mission at the London 2012 Olympics, said: "It has been an amazing four years leading the BOA as the host National Olympic Committee for the London 2012 Games.
"I will always be proud to have led Team GB at a home Games and of the fantastic performance of the team this summer and the way in which the BOA supported the athletes.
"Now that the Games are over, and the organisation's strategy for the next four years is taking shape, the BOA's responsibilities and the job of the CEO are different, and I feel it is the right time for me to move on to another leadership role with breadth and profile similar to the responsibilities I've fulfilled since 2008."
Team GB won 65 medals, including 29 golds, at the London Games to finish third in the medal table.
Hunt will be replaced by Lord Coe as BOA's new chairman
An interim chief executive will not be appointed once Mr Hunt has left. The BOA management team will instead work directly with Lord Coe, the organisation's new chairman.
Lord Coe, who was also chairman of the London 2012 Games organisers, thanked Mr Hunt for his work in preparing British athletes to perform under the pressure of a home Games.
He said: "Team GB had the very best facilities, care and preparation at the London 2012 Games thanks to the tireless efforts and passion of Andy Hunt and his team over the last four years.
"I know I speak on behalf of all Team GB athletes and the BOA board when I say thank you to Andy for the work he has done, and I wish him all the best in his next endeavour."
The modernisation of the organisation and the introduction of business best practices in areas such as corporate governance, strategic and operational planning and the relocation of the organisation's headquarters to central London have all been major events under Hunt's reign.
Sports minister Hugh Robertson said: "Under Andy's direction, the British Olympic Association has undergone a significant transformation and reinforced its reputation as one of the leading national Olympic committees in the world.
"Today, the BOA is recognised as a modern, professional organisation that has as its highest priority serving the needs and interests of athletes and national governing bodies.
"Whilst Andy will be missed at the BOA, he has put in place an operating structure and leadership team that will ensure the organisation continues to move from strength to strength."