Administrators to Jamie Oliver's restaurant chain say 22 sites have closed resulting in 1,000 redundancies after the business collapsed.
KPMG said attempts to bring fresh investment into the celebrity chef's business - at a time of rising costs and fragile consumer confidence - had failed.
The business was left without enough cash to trade while in administration, meaning that all but three of its 25 eateries have closed.
Jamie Oliver said he was "devastated" as the collapse - first reported by Sky News - was announced.
KPMG said Mr Oliver had made additional funds of £4m available since the start of this year as the business sought to attract new investment but after failing to do so "and in light of the very difficult trading environment" appointed administrators.
It said Jamie Oliver's holding company had made arrangements for all restaurant staff salaries to be paid up to the date of the collapse.
The administration encompasses 20 outlets in the Jamie's Italian chain as well as the celebrity chef's remaining Barbecoa site in London and Fifteen London, the restaurant he launched after he was catapulted to fame through his Naked Chef TV programme.
Together they employ approximately 1,300 staff.
Three sites in London's Gatwick airport will continue to trade "in the short term", KPMG said.
International restaurants trading as Jamie's Italian, Jamie's Pizzeria and Jamie's Deli are not affected by the administration process for the UK business.
Fifteen Cornwall, which operates under a franchise, is also unaffected.
The failure of the Jamie Oliver chain comes just two years after it narrowly averted an earlier collapse.
Will Wright, partner at KPMG and joint administrator, said: "The current trading environment for companies across the casual dining sector is as tough as I've ever seen.
"The directors at Jamie Oliver restaurant group have worked tirelessly to stabilise the business against a backdrop of rising costs and brittle consumer confidence.
"However, after a sales process which sought to bring new investment into the business proved unsuccessful, the team took the incredibly difficult decision to appoint administrators."
Jamie Oliver said: "I am deeply saddened by this outcome and would like to thank all of the staff and our suppliers who have put their hearts and souls into this business for over a decade.
"I appreciate how difficult this is for everyone affected.
"I would also like to thank all the customers who have enjoyed and supported us over the last decade, it's been a real pleasure serving you.
"We launched Jamie's Italian in 2008 with the intention of positively disrupting mid-market dining in the UK high street, with great value and much higher quality ingredients, best in class animal welfare standards and an amazing team who shared my passion for great food and service.
"And we did exactly that."
The Jamie's Italian restaurants to close include seven in London, with the rest in Birmingham, Brighton, Cambridge, Cardiff, Edinburgh, Glasgow, Guildford, Leeds, Liverpool, Manchester, Nottingham, Oxford and York.