Murray, who is managing director for group business information strategy at Haymarket, was chairman of the AOP for four years.
He took on the role when it was created in 2002 before passing the reins over to Simon Waldman, Guardian Media Group director of digital strategy, in 2006. He will leave Haymarket at the end of the year and said he planned to explore digital opportunities.
"I've spent half my life here [Haymarket] and have never had another real job. The digital economy presents loads of opportunities despite the current economic climate and the time is right for me to explore the world beyond Haymarket. I have long wondered what I could create for myself and (after a decent Christmas holiday) I am going to find out."
Rupert Heseltine, deputy chairman of Haymarket Group, said: "I want to thank Bill for his commitment and dedication to Haymarket over the last 22 years; he has made a significant contribution to our business, particularly in the consumer magazine division and more recently in our online activities across the whole gtroup.
"I speak on behalf of everyone at Haymarket when I say that Bill will be missed and we wish him continued success in the future."