The group, which includes the Jamie's Italian chain, Barbecoa and Fifteen, has appointed KPMG as administrators.
Twenty two of the 25 restaurants in Jamie Oliver's restaurant group have now closed.
Mr Oliver, who put in £4m cash this year, said: "I appreciate how difficult this is for everyone affected."
Two Jamie's Italian restaurants and Jamie Oliver's Diner at Gatwick Airport will continue to trade in the short term while the administrators explore options for the outlets.
"The group had recently undertaken a process to secure additional investment into the business and, since the beginning of this year, Jamie Oliver has made available additional funds of £4m to support the fundraising," said the administrators in a statement.
"However, with no suitable investment forthcoming and in light of the very difficult current trading environment, the directors resolved to appoint administrators."
Jamie Oliver's Fifteen Cornwall at Watergate Bay, which operates under a franchise, is unaffected. The international restaurants trading as Jamie's Italian, Jamie's Pizzeria and Jamie's Deli will also continue to trade as normal.