Derek Twine, the chief executive of the Scout Association for the past 16 years, is to retire next year.
The association said that Twine was expected to leave in the spring and the process of appointing a replacement would begin this month.
Sir Alan Craft, chair of the Scout Association, said in a statement that Twine, who was awarded the CBE for services to young people in 2007, would be "leaving with our warmest thanks and appreciation".
"Derek has been an outstanding chief executive and his efforts have played a significant part in helping establish the strong position the movement finds itself in today," he said.
Scout membership has grown from 476,568 in 2002 to 525,000 in 2012. The charity had an income of £25.9m in 2011/12 and employs 260 staff.
Chief scout Bear Grylls said: "Derek’s commitment to scouting and to the young people in the movement has been an inspiration to me and I feel very fortunate to have been able to work closely with him during my time as chief scout."