Harcourt owns six hotels in Ireland, including the Titanic Belfast which opens next month, and three of which are in Donegal.
It also owns properties in the UK, Jersey, and the Caribbean.
A spokesman said the firm was “very pleased with the performance of the hotels”.
The hotels side of the business, which has 300,000 rooms to sell a year, account for 25% of the group’s overall activities.
“In 2016 the Irish properties preformed most strongly and were profitable. Room revenue and average spend increased. UK number also increased in occupancy and rate by 7%,” the spokesman said.
The group employs 450 staff in Ireland, 352 in the UK and 257 in the Caribbean.
On the impact of Brexit on the business, the spokesman said: “Our experience so far is positive. Effective marketing of Ireland by Tourism Ireland and Tourism NI are maintaining healthy numbers and we do not detect a downturn.”
He saidd: “For Harcourt, the group’s spread across various jurisdictions helps absorb any fluctuations. Also, our occupancy rates remain high and stable.”
The group’s hotels include the Aspect Hotel in Dublin; Lough Eske Castle in Donegal; the Royal Oasis in the Bahamas; and the Carlisle Bay in Antigua.
The spokesman said that the company is very pleased by the early bookings taken by the Titanic Hotel in Belfast. The 119-room hotel will include a 140-seat restaurant and a themed cocktail bar.