The appointment follows the departure of Nisa boss, Ken Towle, who has joined Big 4 grocer Asda as retail director, after four years at the symbol group retailer.
Fletcher joined Co-op’s food business in 2013, from Tesco, where he held numerous senior positions such as commercial director, over his 22 year stint.
“Michael brings a wealth of experience and already has a good understanding of the wholesale business having been part of the original integration team with responsibility for bringing together and leading the combined wholesale and retail buying teams,” Co-op food chief executive Jo Whitfield said.
At the Co-op, Fletcher was part of the team which acquired Nisa and played a leading role in the decision, the retailer said.
Fletcher said: “I am delighted to take on the leadership of the Nisa business. I know many of the partners and I look forward to meeting many more as we work together to make the very most of an exciting future.”