Sir Philip Green's Arcadia Group has collapsed, putting 13,000 jobs at risk.
The fashion empire, which includes the Topshop, Dorothy Perkins and Burton brands, has hired administrators from Deloitte after the pandemic "severely impacted" sales.
Arcadia, which runs 444 stores in the UK and 22 overseas, said 9,294 employees are currently on furlough. No redundancies have been announced.
Deloitte said the business will continue to trade as normal online and in stores in line with government guidance.
All online orders made over the Black Friday weekend will be honoured, and refunds and gift cards will be processed as per its usual terms and conditions.
Ian Grabiner, chief executive of Arcadia, said: "This is an incredibly sad day for all of our colleagues as well as our suppliers and our many other stakeholders."
The administrators will be "assessing all options available", which could see brands sold off in separate rescue deals.
This includes Burton, Dorothy Perkins, Evans, Miss Selfridge, Topman, Topshop, Wallis and out of town chain Outfit.
What are your gift card rights when a firm goes bust?
Officially, when a firm goes bust, you join the long list of creditors who are owed money by the business.
But, in effect, you join the back of the queue. It’s very rare to actually get any cash back. So for most people, when a firm goes bust, your vouchers and gift cards become worthless.
But, the process of a firm going into administration isn’t usually instantaneous. There's usually a window of opportunity where you can quickly spend the voucher or card before the firm goes under - this is currently the case with Arcadia.
The company is still accepting gift cards however this is likely to change in the coming days.
Adam French, Which? Consumer Rights Expert, said: "Topshop and other Arcadia brands collapsing into administration is yet another serious blow for the high street in what has been a torrid year for retail.
"We would advise any consumers who have vouchers to think about spending them as soon as they can.
"If there is something you are planning to buy from Topshop or other affected brands that is worth more than £100, make sure you use a credit card as you’ll be able to make a claim against your credit card company to recover the money if anything goes wrong."