Flybe, which accounts for 80% of routes out of Belfast City Airport, is set to collapse "within hours", according to reports.
The BBC reported on Wednesday night that 2,000 jobs are at risk after a fresh bid for financial support failed.
The struggling airline was saved from collapse earlier this year but has been unable to obtain the finance from the government.
Flybe has been hit by a slump in bookings since the outbreak of the coronavirus.
Final flights touched down across the UK late on Wednesday night, with Flybe's 8.55pm departure from Belfast City Airport to Glasgow among a number of flights cancelled.
Flybe’s website has stopped working, with visitors being shown as message stating “This link is no longer live.”
The airline flies to 14 UK destinations from Belfast City Airport. A collapse of Flybe would leave Belfast City Airport flying to just four other destinations.
As part of the January rescue deal, Flybe agreed an arrangement to defer tax payments of “less than £10m” with HM Revenue and Customs.
Ministers also agreed to hold a review into air passenger duty (APD).
The structure of APD — which adds £26 to the price of most return domestic flights such as those operated by Flybe — could be altered in next week’s Budget.
Flybe serves around 170 destinations and has a major presence at UK airports such as Aberdeen, Belfast City, Manchester and Southampton.
It flies the most UK domestic routes between airports outside London.
A series of issues have affected the airline’s finances, including rising fuel costs, falling demand, competition from road, rail and other airlines, plus a weakening of the pound.
It was bought by a consortium comprising Virgin Atlantic, Stobart Group and Cyrus Capital in February 2019, but has continued to make losses.
Rival Ryanair has predicted the drop in demand for flights due to the coronavirus will result in some European airlines failing in the coming weeks.
Earlier on Wednesday, a Belfast City Airport spokesperson directed all queries to Flybe.
A Flybe spokesman would not comment on its financial situation.
A Department for Transport spokeswoman said: “We won’t comment on speculation.”
At the time of Flybe’s rescue, rival airlines complained that they should not be penalised for their own success and they should also be given a tax holiday.
British Airways owner International Airlines Group claimed the arrangements breached state aid rules.