Ballymena-based firm JBE Mechanical Electrical has announced it will close after it went into administration.
The firm's administrator said 57 staff would be made redundant.
Staff were told about the job losses on Friday at a staff meeting at the firm's headquarters at the Braid River Business Park.
It went into administration last Thursday, when the administrator began assessing the options available for the firm.
"Unfortunately, following our review of live contracts and the company order book, I have concluded that it is not feasible to continue trading the business in administration," said Gerard Gildernew, JBE Mechanical Electrical's administrator.
The business, which was set up in 1983, was one of Northern Ireland's longest established electrical and mechanical contractors.
It worked across the commercial, industrial, leisure, healthcare and retail sectors.
The administrator has been liaising with Ballymena Jobs and Benefits office, which is providing assistance to affected staff, according to a statement from the company.