Marks & Spencer boss Marc Bolland is to bow out in April after a six-year battle to turn around the high street giant as it revealed a dire Christmas performance from its womenswear division.
Mr Bolland will be replaced by M&S veteran Steve Rowe, who has been with the group for more than 25 years and was recently promoted to head its general merchandise business.
Details of the change at the top came as M&S revealed that like-for-like sales in its general merchandise arm, which includes clothing, slumped by 5.8% in the 13 weeks to December 26.
It blamed the tumble on unusually mild weather and poor stock availability.
Mr Bolland said it had been "a huge honour to lead one of Britain's most iconic companies".
He added: "I am delighted to hand over to Steve Rowe as my successor. I have worked closely with Steve for six years and I am convinced that he will be a great leader for Marks & Spencer."
M&S chairman Robert Swannell paid tribute to Mr Bolland's achievements and insisted Mr Bolland was not under pressure to quit from shareholders or the board.
Succession planning had been in train "for years", Mr Swannell said, adding that the process had been " rigorous" .
Mr Bolland, who took on the post of chief executive in early 2010, will retire at the end of the group's financial year on April 2, but will remain on hand to help with the handover until the end of June.
Mr Swannell said: " Over the last six years Marc Bolland has led Marks & Spencer through a period of necessary change.
"It is now positioned for a digital age, with its own online platform and dedicated e-commerce distribution centre, improved design and sourcing capabilities in general merchandise and an industry-leading track record of growth and innovation in the food business."
But further woes in the group's troubled clothing division highlight Mr Bolland's struggle to revive trading, with the outgoing boss admitting the general merchandise performance over the festive season was "disappointing".
The fall in like-for-like sales, which followed a 1.9% drop in the previous three months, came as the group resisted pressure to discount early despite widespread sales launched on the high street.
It also suffered a shortage of lighter-weight clothing as shoppers shunned thick winter coats.
The group said its move to hold off from launching early promotional sales helped protect profits, while t here was also better news from the chain's food halls.
It hailed its "best ever Christmas" for the food division, with a 0.4% rise in like-for-like sales over the quarter to December 26 against challenging conditions in the sector.
But retail expert Clive Black, at Shore Capital, said the Christmas performance by M&S's general merchandise business was "demonstrably disappointing" and weaker even than rival Next, which shocked the market earlier this week with a fall in festive store sales and sharp slowdown in its Directory catalogue and online arm.