Sainsbury's is shutting its Milton Keynes office after a shift to flexible working left almost nine in ten desks empty.
Britain's second largest supermarket said it would be closing the offices – historically the headquarters of Argos – within the coming months.
The company blamed the closure on the shift towards flexible working, saying only 11pc of desk space was being used regularly.
LinkedIn data suggests hundreds of people were based in the office, although Sainsbury's is understood to currently only be using one floor. Sainsbury's announced the closure as part of a wider round of cost cutting. The supermarket said it would close two Argos warehouses, putting 1,400 jobs at risk.
A depot in Heywood, Greater Manchester and a distribution centre in Essex will both be shut within the next three years.
Workers from both Sainsbury's and Argos are expected to be affected by the planned changes, as well as HGV drivers employed by Wincanton.
Simon Roberts, chief executive at the UK's second largest supermarket, said the decision to consolidate five warehouses to three came as part of efforts to merge the Argos and Sainsbury's operations.
The restructure will allow the company to cut costs "so we can invest where it will make the most impact for our customers".
Like other major supermarkets, Sainsbury's has been cutting and matching prices amid a fierce battle for customers.
Profits at the group fell by a third in its most recent set of results.
Union chiefs blasted the plans, saying there was "no economic justification" for the job losses.
Unite national officer Matt Draper said: “Management at Argos/Sainsbury’s has yet to provide any form of business case for the loss of these jobs.
"Unite will be fighting to preserve every job and will put forward an alternative business case to the company to preserve employment at these two sites."
Sainsbury's, which bought Argos for £1.4bn in 2016, said it was consulting closely with unions on the closures.
Mr Roberts said: “We understand that this will be an unsettling time for affected colleagues, and we will support them however we can throughout this process."
The supermarket has already moved to save costs by closing fresh food counters and cafes. It is also closing the three remaining Habitat showrooms that it still operates.