ALL 531 standalone Carphone Warehouse stores will be closed — meaning 2,900 redundancies.
Dixons Carphone said the market was changing and its restructure would create £1 billion free cash flow by 2024.
The mobile phone firm, which has standalone branches at Parkgate Shopping and Bramley, said customers were replacing handsets less often.
That part of the business is expected to make a loss of £90 million this year, the company added.
Group chief executive Alex Baldock said: “Customers are changing how they buy technology, and Dixons Carphone must change with them. We’re under way with a fundamental transformation to do so.
“I don’t underestimate how upsetting this news will be for our colleagues, and we’ll treat everyone with honesty, respect and care.
“We want to keep as many of our colleagues as we can, and expect to find new roles for almost 40 per cent of those affected.”
The Carphone Warehouse “shops-in-shops” — such as its other Parkgate Shopping branch — are said to be unaffected.