The Brinks security cash-in-transit company is to close its Republic of Ireland operation with the loss of 201 jobs, mostly in Dublin.
A company spokesperson has stressed the closure will be an orderly wind down, and all bills will be paid.
Staff are currently being notified of the closure.
A spokesperson said the Irish cash-in-transit market has not been profitable for them in recent years, and they do not see it as a sector that will provide opportunities for growth going forward.
The spokesperson did not have details of the terms of any redundancy package.
Customers will be given a period of time, believed to be four weeks, to re-tender for cash-in-transit services from alternative suppliers.
Most of the company's operation is based in Cloughran in Dublin.
The company’s Northern Ireland operation is not affected by the decision.
SIPTU Organiser Brendan Carr has condemned the announcement, saying last month the union had finalised an agreement with management "on a major restructuring deal which we were ensured would safeguard the company's future in Ireland."
He blamed "low-cost employers in the security industry" who "do not adhere to the established terms and conditions of employment in the cash in transit sector" for endangering jobs.
Mr Carr added SIPTU "will now work towards securing employment for as many of these workers as possible in this specialised industry".