816 jobs have been announced by EY.
606 of the roles will be based at its office in Dublin.
Many of the roles are expected to be filled by June next year.
The company is looking to hire across its core areas of tax, audit, corporate finance and consulting as well as in new areas including technology consulting, digital and emerging technology, data analytics, cyber security, sustainability, law, strategy and transformation.
EY Ireland said increasing demand for its services and fundamental changes brought about by the pandemic, were key to its decision to expand.
Separately, 100 jobs are being created by pharma company AstraZeneca.
The firm is investing more than 300 million euro in a facility in Dublin.
AstraZeneca claims the move to Ireland will help it in its zero-carbon ambitions.
