Rob Norman is retiring after more than three decades in the advertising business, where he helped clients and colleagues navigate industry changes brought on by new technology and media players.

Mr. Norman has spent 31 years with WPP media agency network GroupM and CIA, a media buying shop that WPP acquired in 2001.

Mr. Norman, who currently serves as global chief digital officer and North American chairman for GroupM, will leave his full-time role in January. He’ll continue to consult with GroupM and its clients, with a “lessened workload allowing him more time for pursuit of his many personal interests,” the company said in a statement.

 
“GroupM, WPP and before that CIA have been my work, my life and almost always my pleasure,” said Mr. Norman, who is 57 years old, in the statement. “My friends in the business know that I’ve become very attached to a rural life and understand that after 31 years, it’s time to do other things. It’s a curiosity of our business that few people get to step back, yet stay involved; I’m honored that GroupM is allowing me to do exactly that.”

Mr. Norman has been focused on helping GroupM’s clients keep up with the rapid pace of evolution in digital media as technology upends the agency business. As he explains it, he has spent most of his time trying to understand “who and why, and to what effect, disrupters” like Amazon, for example, have on companies like Nestlé or NBCUniversal. Then, he helps “synthesize that information in a way that’s relevant to clients,” he said in an interview.

Mr. Norman is also a regular presence at ad industry conferences and WPP events, where he’s known for his sharp sense of humor and sweeping thoughts on the pitfalls and opportunities of online advertising.

GroupM, which owns media buying shops Mindshare, Mediacom and Essence, said it isn’t replacing Mr. Norman.

Mr. Norman said that in retirement he’ll spend about 15% of his time consulting with GroupM, and he’ll likely continue to speak at industry events. The rest of the time, he’ll mostly be at his home in Connecticut, where there’s less noise and it’s easier to think about the large issues affecting the world, he said.

“My relationships with clients and senior partners at the Googles and Facebooks have never been better than they are now in some respects,” he said. “I’d rather do this now, and move on to the next act while I’m at the top of my game, rather than build relationships based on who I used to be.”

The change comes as GroupM undergoes its own transformation. Kelly Clark took on the global CEO role in 2016, replacing former GroupM boss Dominic Proctor. Since then, the group has consolidated agencies, absolving Maxus into MEC, and it’s focused heavily on boosting “transparent” digital buying group [m]PLATFORM to appeal to clients who are increasingly asking for more visibility around the digital buying process and its costs.

“Happily, this is not goodbye,” said Mr. Clark in the statement. “We still take this opportunity to thank Rob for his loyal service and for continuing to share his passion and vision for this business as GroupM and the industry continue to evolve.”