Fellows was previously at agency TBA, where he held a senior business development and and client relationship role for three years. He bagged a spot on the Event 100 Club in December 2015.
Nick Robinson, managing director of Concerto Live, said: "Great relationships have always been key to our success as an agency, so we're delighted to have someone of Max's calibre joining our senior management team to lead client services across the business. He has a deep understanding of live communications, backed-up by years of experience developing relationships with premium brands."
Fellows added: "I've been blown away by the energy and creativity of the Concerto Live team; they're producing some seriously impressive work for some great brands. I've always believed that a successful agency is built by teams that are inquisitive, innovative and understand the brands they work with.
"These guys have nailed that whilst fostering a collaborative culture of fun, backed up by a reputation for flawless delivery. That's why I'm so thrilled to be joining the team at such pivotal and exciting time, with big plans on the horizon."
Concerto announced Sam Gill as its chief executive earlier this month.
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