Mivan has been placed in administration putting nearly 300 jobs at risk.
The move follows the collapse of rescue talks with rival Lagan late last year.
Sources close to the firm told the Enquirer that staff were given the bad news this morning.
Workers were also told that their wages can only be guaranteed until next week.
Mivan is one of the biggest contractors in Northern Ireland with a large presence in the UK.
Mivan chief executive Ivan McCabrey said: “The directors have been reviewing future options in conjunction with our bankers and professional advisers.
“It is with regret therefore; that the directors have today sought the protection of administration in order to preserve the future options of the business.”
Mivan made its name in the international contracting arena on high-end projects, often in the Middle East, but has struggled in recent years after some overseas property investments backfired.
More recently Mivan has been concentrating on fit-out jobs in the UK. Construction Enquirer.