Parsons will start his new role in January 2015, leading everyday management across GMR’s hubs in the Americas, EMEA and Asia Pacific.
Parsons joined GMR as managing director international in 2005.
Before that, he served as both the director of operations for DAS Global in China and as GMR’s MD in Asia Pacific.
Parsons said: "GMR’s award-winning work and strong client relationships are a testament to Gary’s leadership. The opportunity to take his vision to the next level is an honour. I’m looking forward to enhancing GMR’s existing client partnerships and building new ones as we continue on our path to be the most significant and dynamic marketing agency in the world."
In his new role, Reynolds will provide strategic, day-to-day counsel.
Reynolds said: "As GMR’s footprint continues to grow, the need for management that can deliver true global strategy and leadership is crucial. Cameron’s extensive breadth of experience and success make him the perfect person to take GMR and its clients to the next level."