Marks & Spencer is swapping plastic carrier bags for paper ones in all stores, in an expansion of a trial that began in 10 branches in January.
It follows other High Street stores in swapping plastic bags to paper in a bid to cut plastics use.
Supermarkets Morrisons, Waitrose and Aldi all use paper bags for customers, though some stores offer plastic bags as an option.
Marks & Spencer has more than 1,000 stores nationwide.
The retailer said it had worked with the University of Sheffield to develop a bag that is made using renewable energy, since paper is more energy-intensive to produce than plastic.