Accountancy company EY has announced that it is to create 270 jobs in Dublin, Cork, Limerick, Waterford and Galway.
The company, formerly known as Ernst & Young and which already employs 1,800 people in Ireland, has said the growth is being fuelled by high demand for services such as cyber security and fraud investigation.
The positions are across a range of divisions, including accounting, finance, engineering, IT, consultancy and business.
220 jobs will be for experienced professionals, while another 50 will be extra graduates on top of the 200 the firm normally recruits every September.
The expansion also sees the company open a second office in Dublin, and a centre in Eyre Square in Galway which will employ 25 people.
The company is also planning to expand its operation in Limerick.
It said it had seen a rise in demand for a range of services including data analytics, fraud investigation and cyber security.
The company has grown its business in Ireland by 16% every year over the past three years, and its workforce has increased by a quarter since 2014.
It said the starting salaries for the new positions will be €50,000 a year.
The announcement has been welcomed by Minister for Jobs, Enterprise and Innovation Mary Mitchell O'Connor, who said it was a true mark of confidence in the Irish economy and a boost for the regions.
Country Managing Partner for EY Ireland Mike McKerr said the company was recruiting at all levels, from graduate through to directors and partners and requires a mix of talent to meet client needs.
