He told PRWeek: "It’s time for a change. I’ve been here 15 years and it’s time to do something new."
Regarding his future plans, Wilson said: "I am looking forward to a break and then will decide what I want to do longer term.
"I’m sure I’ll stay in communications, but in which facet, in what guise… I just want to take some time out to make that decision."
Wilson said he believed his role would be consolidated into other positions for the time being.
Wilson joined in 2000 to lead the agency’s account with Emirates Airline. He became managing director of Bell Pottinger Public Relations in 2002, subsequently becoming its chairman.
Wilson assumed the MD role at Bell Pottinger Group in 2011 as part of a new management board. Late last year his role was expanded to include chairman of Bell Pottinger’s consumer practice.
Wilson said: "I’ve enjoyed a tremendous time at Bell Pottinger and wish everyone in the company every success going forward, not least given I’ll continue to be a shareholder. However it’s now time for me to take a break and decide what I’d like to do in the future."
James Henderson, Bell Pottinger Group CEO, said: "David has played a pivotal role in the growth and development of many areas of Bell Pottinger and we are very sad to see him go, but he will always be a friend of our business."
Before joining the agency, Wilson, a former journalist, spent time as head of corporate comms at Pfizer UK, head of news at British Airways, and PR manager at P&O.