David Biddle, chief executive of the health and social care charity change, grow, live, is to stand down after 21 years with the charity.
A spokeswoman for the charity said Biddle, who has been chief executive of the charity for the past four years and deputy for the previous 17, said it was the "right time to hand over to someone who can take CGL through the next phase of its development".
Biddle will take a break after he stands down in March or April and then "work on other projects outside the sector, but close to his heart", the spokeswoman said.
CGL, which changed its name from Crime Reduction Initiatives last year, has grown rapidly in recent years, with income rising from £80.8m in the year to the end of March 2012 to £158.3m in 2015/16.
Biddle said he would be standing down at the right time with a new strategic planning cycle due to start when he leaves.
"The past 21 years at CGL has been a remarkable experience," he said. "CGL has been a major part of my life, but this is the right time to hand over to a new leader, someone who can lead the strategic direction of this organisation in the next phase of its development.
"I have no doubt CGL will continue to go from strength to strength."
The charity has begun the process of recruiting Biddle’s successor.