Carphone Warehouse has announced it will close all of its 531 standalone stores, resulting in nearly 3,000 job losses.
The mobile phone retailer said it was not because of the Coronavirus outbreak, stressing it was due to changes in the mobile phone market.
It will continue to operate within 305 Currys and PC World stores, and around 1,800 staff are expected to take on new roles in another part of the business.
Group chief executive Alex Baldock said customers are increasingly purchasing mobile phones or upgrading their contracts online or within larger stores.
He said: "They can't find all this in the small mobile-only stores that are one-twentieth of the size; they're visiting these less and these stores are losing more money as a result."
The company said it is an "essential next step" to ensure its future, with an expected £90 million loss this year.
Mr Baldock added: "I don't underestimate how upsetting this news will be for our colleagues, and we'll treat everyone with honesty, respect and care.
"But though this is by far the toughest decision we've had to make, it is necessary. We must follow our customers. They want help with all technology, all in one place, and this trend is only going to accelerate in a more connected 5G world."
Speaking to the BBC, he said: "The coronavirus and uncertain outlook ahead has underlined the importance of acting decisively, but no, the driver here is what we're seeing from customers.
"We have to take the difficult decisions to throw our weight behind the parts of the business that the customers are showing us they want... that's with the big stores and that's online."