Administrators have been appointed to begin "an orderly wind-down" of the UK's biggest toy retailer following the failure to find a buyer. They said that all 105 Toys R Us stores will remain open until further notice.
Joint administrator Simon Thomas said: "Whilst this process is likely to affect many Toys R Us staff, whether some or all of the stores will close remains to be decided."
Toys R Us has been facing a €17m (£15m) tax bill. However, poor sales have made it unlikely that it can make the payment.
Mr Thomas said: "We will make every effort to secure a buyer for all or part of the business. The newer, smaller, more interactive stores in the portfolio have been outperforming the older warehouse-style stores that were opened in the 1980s and 1990s."
A large sale of remaining products at Toys R Us is expected. The administrators said this would happen in stores only, as the online service and click-and-collect will be closed immediately.
Shoppers who have ordered an item already on click-and-collect can still pick it up, but only if that item is still available in stock. Anyone with Toys R Us gift cards and vouchers should spend them in stores as soon as possible before the shops are closed down. No more gift cards will be sold.
The retailer had a "take time to pay" service, which allowed customers to reserve a product and then pay for it gradually for 12 weeks, before picking it up. The administrators said these reservations would be honoured, provided that the outstanding balance was paid and the goods collected by 11 March. Alternatively, customers can use their deposits towards the cost of any other item bought in a store by 11 March.
The UK arm of Toys R Us - its US owner filed for bankruptcy protection last September - managed to stave off administration in December after it struck an agreement with the Pension Protection Fund (PPF) to inject £9.8m into its retirement scheme over three years.
The scheme has a shortfall of €43m (£38m) which will now be transferred over to the PPF.
People who have already retired will receive 100% of their pension payments, while whose still working will get 90%.
Andy McKinnon, acting chief executive at the PPF, said: "We will now be working to maximise the recovery to the scheme from the administration. Members of the Toys R Us pension scheme can be reassured that the PPF is there to protect them."