Clothing chain Peacocks fell into administration, putting some 9,600 jobs at risk.
The owner of Peacocks said on Monday that it planned the move after discussions with lenders broke down.
Professional services firm KPMG said on Wednesday it had been appointed administrator to Peacocks, which owns 611 stores and 49 concessions across the UK, as well as its parent company The Peacock Group.
KPMG said all Peacocks stores remain open as it seeks to find a buyer for the business and no redundancies have been made.
Meanwhile, KPMG said Bonmarche, also owned by The Peacock Group, which employs 3,800 staff and operates some 394 stores, has not entered administration and a buyer is being sought for the business.
Bonmarche filed a notice of intention to appoint administrators on Monday but this allows 10 working days before the appointment of administrators.
Chris Laverty, joint administrator and restructuring partner at KPMG, said: "Like many retailers Peacocks has suffered from tough economic conditions, which have seen its customers reduce their spending on the high street.
"This factor, combined with a surplus of stores and high overheads, led to the business becoming financially unviable in its current form."
The Cardiff-based retailer reportedly failed to persuade its lenders - including Barclays and Royal Bank of Scotland - to enter a debt for equity deal.
However, after the announcement was made, a spokesman for Barclays said: "This is not the end for Peacocks, there is a viable business here and our support continues."
Peacocks, owned by hedge funds Och-Ziff and Perry Capital, has been boosted by the success of a collaboration with the singer-turned-fashion designer Pearl Lowe. Like-for-like sales rose 17% over the Christmas period and the company said it was benefiting from its ability to react quickly to fashion trends.
The exact amount of the debt within the business remained unclear but £647 million of borrowings was reported to be within the business at the end of April 2010.
KPMG has overseen the administration of several retail firms in recent weeks including outdoor retailer Blacks Leisure, gift retailer Past Times and lingerie firm La Senza.
The administration of Peacocks is one of the biggest since administrators were appointed to Woolworths in December 2008, leading to several tranches of closures which left 27,000 employees out of work.
Peacocks can trace its history back to Warrington, in Cheshire, in 1884 when Albert Frank Peacock founded Peacock's Penny Bazaar. In 1940, Mr Peacock's son Harold moved the business to its current base in Cardiff.
The business developed and expanded in the nineties, floating on the London Stock Exchange in 1999. The Peacock Group acquired low-cost retailer Bonmarche in 2002.
The company delisted from the stock exchange to once again become a privately owned business in 2006 and broke the 500 stores mark in 2008.