The budget operator had seen flights grounded since falling into bankruptcy for the second time in three years at the end of last month.
There had been speculation Lufthansa and Air France-KLM were in talks with administrators to take over the firm.
However, Birmingham-based Flybe said discussions had ended without a new deal being agreed.
It said it would start winding-down the business, with administrators adding a further 25 employees would be made redundant immediately.
They are on top of the 277 of Flybe's 321 staff members whose redundancies were previously confirmed by joint administrators Interpath Advisory.
"Over the past two and a half weeks, we've held intensive discussions with a number of operators with a view to rescuing the airline and preserving the value in its assets," David Pike, managing director at Interpath said.
"However, it is with regret that discussions have now been brought to a close without a deal being agreed."
Despite interest from a number of credible parties, administrators said challenging circumstances, complexities and high costs associated with the company's operating platform meant a suitable buyer could not be found.
"We'd like to thank a number of stakeholders, including the Civil Aviation Authority (CAA) and the company's lessors, who gave us the time and support we needed to ensure we were able to explore every available avenue to rescue the business," they added.
Administrators said they would continue to provide support to all employees affected, adding they were grateful to organisations across the aviation industry which had offered to support them in finding new roles.
Flybe was first pushed into administration in March 2020 with the loss of 2,400 jobs as the Covid-19 pandemic destroyed large parts of the travel sector.
Its business and assets were purchased in April 2021 by Thyme Opco, linked to US hedge fund Cyrus Capital.
Flights resumed 12 months later, with the airline based at Birmingham Airport.