The group, which runs Littlewoods, Kays and Woolworths.co.uk, is to slash 900 positions in Sunderland.
Other jobs will go in Burnley and Newtown, Wales, as the company seeks to cut costs.
The union is now in a 90-day consultation with company chiefs over the job losses. The latest job cuts announcement comes a year after it trimmed its workforce by 1,150 positions.
It also bought the Woolworths name in the UK following that firm’s closure, which it has turned into an internet retailer GMB Northern regional officer Mick Hopper said: “This is disastrous for the communities where these jobs will be lost and we will make the decision as costly as we can for the company by demanding higher redundancy payments.
“It was horrible when we told the workers, people were crying and it is just such a devastating blow.
“There had been extra overtime recently so we had no idea that these job losses were around the corner.”
Shop Direct was formerly known as Littlewoods Home Shopping.