Clarke, who has been at the helm for three years, will be replaced by Unilever executive and turnaround specialist Dave Lewis, Tesco said in a statement, as the group struggles with what it described as “challenging” trade.
“Tesco announces that Dave Lewis will join the board of Tesco on October 1 as CEO in succession to Philip Clarke,” the company said.
“Philip Clarke will continue as CEO until that date when he will step down from the board but will continue to be available to support the transition until the end of January 2015.”
Tesco faces fierce competition in Britain from German-owned discounters Aldi and Lidl, as well as from traditional supermarket rivals comprising Walmart division Asda, Sainsbury’s, Morrisons, and Waitrose.
The group had revealed in June that it suffered its worst British sales performance for 40 years in the first quarter.
And in April, the group posted the second drop in annual profits in a row, hit by difficult trade in Europe and a costly investment plan that was aimed at turning around its domestic business in Britain.
Tesco is the world’s third biggest supermarket group after French rival, Carrefour, and with US retailer, Walmart, in first place.