Fidelity is to add 200 new positions at its offices in Dublin and Galway.
The financial services company already employs 500 people here.
It is looking for a mix of professionals in technology, back-office operations and enterprise services.
The initiative will see a major investment by the firm and is supported by the IDA.
In addition to more than 300 mutual funds the firm also offers discount brokerage services, retirement services, estate planning, wealth management, securities execution and clearance and life insurance.
Fidelity Investments Ireland was established in 1996 as the European offshore development centre for Fidelity Investments and now employs over 350 people here.
Its technology associates in Ireland support multiple business divisions in the U.S., Europe and Asia including Asset Management, Corporate Technology, Information Security and Enterprise Infrastructure.
Last year Fidelity hired 250 people after an initial recruitment drive for 100 staff.
Travis Carpico is Chief Executive of Fidelity Investments Ireland.
He says this arm of its operations is highly valuable to the company.