He is being succeeded in one of the most high profile jobs in British business by M&S's food boss and joint chief operating officer Stuart Machin, who will become chief executive and take on responsibility for day-to-day leadership of the business and executive committee.
An unconventional leadership structure will see Machin backed up by co-chief executive Katie Bickerstaffe and finance and strategy chief Eoin Tonge.
Rise To The Top
Machin, 51, joined M&S as food managing director in April 2018 and was appointed joint chief operating officer in May last year.
He has led the team responsible for reviving M&S's food business through a focus on improving value, without compromising the quality, welfare and sourcing standards the retailer is known for, and by driving innovation.
M&S is currently Britain's fastest growing food retailer apart from discounters Aldi and Lidl, according to industry data.
It announced a pretax profit of £522.9 million (€614 million) in the year to April 2.
Machin began his retail career as a teenager, stacking shelves at a Sainsbury's Savacentre in Hempstead Valley, south east England. He then rose up the ranks with senior operational and commercial roles at Sainsbury’s, Tesco and Asda.
More recently, he spent ten years in Australia working at conglomerate Wesfarmers as operations director and managing director of Coles and Target respectively. Before joining M&S, he was CEO of Steinhoff UK.
Machin abruptly resigned as managing director of Wesfarmers' Target in April 2016 after concerns were raised regarding its accounting for commercial income.
He said he was dismayed to learn of the accounting issues and was not aware of them but resigned as "they happened on my watch".
Friends In High Places
M&S chairman Archie Norman has been a long term mentor of Machin. They worked together at Asda when Norman was chairman and in Australia at Coles when he was a non-executive director.
Another mentor is Jan du Plessis, the former BT chairman and former M&S non-executive director. Machin says they talk every month.
A resident of south London, outside of work Machin's hobbies are music and walking his dog, Kostas.