Tesco chief executive Sir Terry Leahy will step down next March after 14 years leading Britain's biggest supermarket.
Sir Terry is to be succeeded in the top job by international and IT director Philip Clarke, who has worked at Tesco throughout his career, having started as a part-time assistant in 1974.
The chain's outgoing boss, who will be 55 when he retires in March 2011, said he joined the group with a plan to make Tesco number one in the UK and to build long-term growth by expanding into non-food and internationally.
He said: "When I became chief executive I had a plan to build Tesco around its customers, to make it number one in the UK and to find new long-term growth in non-food, in services and in international expansion.
"I wanted to develop a purpose and values that could sustain Tesco through its challenges and encourage and grow future leaders. It has taken 14 years but that strategy has become a firm reality now and so I feel my work is almost complete."
Sir Terry said he would concentrate on "private investment" after he left Tesco, but would retain a large shareholding in the firm. Shares in the supermarket dropped nearly 2 per cent after news of his departure broke.