Up to 450 jobs are to be created over the next four years in Dublin and Cork.
Accounting and consulting firm Deloitte will create 400 posts over the next four years as it expands its consulting business.
It is seeking to recruit 100 staff immediately with a further 300 over the coming years, mostly in Dublin.
Roles are available in areas such as big-data analytics, digital design, finance, financial technology and customer strategy.
Deloitte has offices in Dublin, Cork and Limerick.
Deloitte has also confirmed that the Competition and Consumer Protection Commission has approved the acquisition by Deloitte of System Dynamics, which is one of Ireland's biggest technology consulting businesses.
Separately, 50 new high-end research positions are to be created in Cork at APC's new Microbiome Institute, which is officially being opened today.
Microbiome is a collaboration between UCC, Teagasc and Cork Institute of Technology.
APC was formerly known as Alimentary Pharmabiotic Centre but will now be named the APC Microbiome Institute.
It explores the importance of microbes in health and nutrition.