Around 300 new jobs are to be established in Dublin and Cork, it was announced.
Software security company FireEye will create 150 jobs with a new technical support centre in Cork.
FireEye, which provides web and email software protection, is expected to begin recruitment immediately.
The investment is supported by the Department of Jobs, Enterprise and Innovation through IDA Ireland.
The company said that the support engineer jobs will be focused on the Europe, Middle East and Africa region.
Jobs Minister Richard Bruton said the announcement was "a great boost for the city and a further indication of what is possible in this sector for Ireland".
Elsewhere, marketing software company Hub Spot has announced the creation of 150 jobs in Dublin.
There will be posts in sales, support, marketing, engineering and development roles.
The company currently employs a team of 22 staff in Dublin.