Marks and Spencer said it will cut the number of its clothing and home stores by around 60 in the UK, as it posted an 88% plunge in half year profit.
Chief executive Steve Rowe said the move is part of his turnaround plan for the retailer, and will mean the closure of 30 stores offering all M&S food, clothing and homeware ranges.
The measure will also see the high street stalwart change a further 45 stores to sell only food, over the next five years.
M&S also reported its pre-tax profit tumbled to £25.1m ($31.2m) in the six months to the end of September as sales of clothing and food declined. It also faced a number of restructuring and pensions costs.
The group has seen sales in its key UK clothing division fall for most of the last five years, under intense competition from rivals such as Next, Hennes & Mauritz and Zara.
Rowe, who took over from Dutchman Marc Bolland in April, said: "These are tough decisions, but vital to building a future M&S that is simpler, more relevant, multi-channel and focused on delivering sustainable returns."
The cost of the programme would be £50m for the next three years, rising to about £100m pounds in years four and five.
The retailer currently has over 300 full-range sites and nearly 600 Simply Food shops in the UK.
The retailer also plans to shut 53 stores across 10 international markets - including 10 in China and seven in France, while pulling out of Belgium, Estonia, Hungary and Lithuania - putting around 2,100 jobs at risk. It declined to say how many jobs might go as part of its UK store closures.
The latest restructure come as M&S revealed more sales falls in its embattled clothing division, with like-for-like sales down by 5.9% in the first half.
But it narrowed the sales decline from 8.9% in the first quarter - its worst performance for a decade - to 2.9% in the second quarter.
Same-store food sales fell 0.9% over the half-year, while it saw growth of 0.3% at M&S.com, leaving overall UK like-for-like sales 3% lower.