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 high street giant, which includes the Topshop, Dorothy Perkins and Burton brands, has hired administrators from Deloitte after the pandemic "severely impacted" sales across its brands.
The group, which runs 444 stores in the UK and 22 overseas, said 9,294 employees are currently on furlough.
No redundancies are being announced yet as a result of the appointment and stores will continue to trade, the administrators said.
In his statement Mr Grabiner continued: “The impact of the Covid-19 pandemic, including the forced closure of our stores for prolonged periods, has severely impacted on trading across all of our brands.
"Throughout this immensely challenging time our priority has been to protect jobs and preserve the financial stability of the group in the hope that we could ride out the pandemic and come out fighting on the other side.
"Ultimately, however, in the face of the most difficult trading conditions we have ever experienced, the obstacles we encountered were far too severe."
Matt Smith, joint administrator at Deloitte, said: "We will now work with the existing management team and broader stakeholders to assess all options available for the future of the
"It is our intention to continue to trade all of the brands, and we look forward to welcoming customers back into stores when many of them are allowed to reopen."