White Young Green, the multi-disciplinary consultancy, has posted a 32% increase in revenue.
Results for the year to the end of June show group revenue rose to £220.6m.
And the GB-based group's Ireland operation, which includes offices in Belfast and Londonderry, made a healthy contribution to the overall revenue figure - £35m (a 54% increase).
WYG, a consultant to the built, natural and social environment, enjoyed a 37% increase in profit before tax and acquired intangible amortisation to £16m.
Pre-tax profit came in at £13.4m - a 21% uplift - and there was a 23% increase in the net order book to a record £380m.
Ray Moore, group managing director of White Young Green Ireland, said the increase in revenue in Ireland was generated by a mixture of acquisitions and organic growth.
The company has a staff of over 500 located in offices in Athlone, Belfast, Cork, Derry, Dublin, Kilkenny, Limerick, Sligo and Waterford, and works for many of the leading private and public sector organisations throughout the island of Ireland.
Contract wins in Northern Ireland have covered hospital construction projects, apartment, hotel and office developments, assisting in the delivery of a wastewater framework and a programme of health and safety audits.
"We have continued to sustain the momentum of growth built up by White Young Green in Ireland over the past number of years," said Mr Moore.
"These results demonstrate that we are again well positioned to continue on our path to provide an ever growing portfolio of services and expertise related to the built, natural and social environment."