Mayo, who is credited with helping establish the Fairtrade mark, spent 11 years as CEO of the New Economics Foundation before moving to lead the NCC in 2003. The NCC merged with Postwatch and Energywatch in October and has been renamed Consumer Focus.
As CEO of Co-operatives UK, the umbrella group for The Co-operative Movement, Mayo will be responsible for building support among business leaders, politicians, workers and consumers for a more co-operative economy and society.
"Those who know me will also know that building an ethical economy is something I have long been passionate about, from helping to start the Fairtrade mark through to my recent book, Consumer Kids," Mayo wrote on his blog. "The world would be a better place with a little more co-operation and I am really privileged to have been offered the role - not to say a little nervous."
The chairman of Co-operatives UK and CEO of Midcounties Co-operative Society, Ben Reid, added: "We are looking forward to working with Ed over the coming years. His dedication to co-operatives will be a great asset as we continue to demonstrate the value of business co-operation to the UK economy."
Dame Pauline announced her retirement in October last year after nine years in the role.