The re-shuffle was announced just a week after the resignation of Co-op chief executive Euan Sutherland, a Scot, who branded the 170 year-old group "ungovernable".
The Co-op said Mark Craig, director of co-operative relations, will be leaving the group after spending his entire 30 year career in the co-operative movement.
Meanwhile, Martyn Hulme, managing director of Co-operative Estates who has spent 20 years at Co-op has been removed from its executive committee but will remain with the group. He will now report to Steve Murrells, chief executive for retail, who keeps responsibility for food, pharmacy, farms and online but will also take on property and estates.
Mr Murrells joined Co-op in 2012, having run Danish meat company Tulip and previously had a long career with Tesco. He has been critical of Co-op's past performance claiming it has been "suffering from coronary heart disease" for 50 years.
Also exiting the top table but staying with Co-op are Andy Haywood, the former HBOS retail bank chief information officer, who does that role for Co-op and Gill Barr, group marketing director.
Ms Barr will report in to Nick Folland, chief external affairs officer, who will add oversight of membership and social goals to his existing role running communications.
Former Barclays staff Rebecca Skitt, who joined as chief human resources officer last year is leaving Co-op. Her replacement is Sam Walker, previously HR director for group functions.
Rod Bulmer will join the management executive as chief executive for consumer services in June, with responsibility for general insurance, funeralcare and legal services. He is currently deputy chief executive at Co-op Bank.
Mr Pennycook will take on a wide-ranging role as chief operating officer overseeing finance and procurement, information technology and risk.
He said the management changes "mean we are better positioned to tackle the complex issues we face".