Some 190 jobs are to be created with the expansion of separate companies in Dublin and Galway.
SmartBear, a software firm, said it will take on 100 new staff over the next five years at its new European HQ in Galway.
Jobs Minister Richard Bruton described it as a great boost. "This builds on the significant progress we have seen in the job market in the past two years, and I wish them every success with this project," he added.
The investment is being backed by the taxpayer through the State investment agency IDA Ireland.
Headquartered in Beverly, Massachusetts, in the US, SmartBear develops software for online applications.
It has customers in over 90 countries and offices in the United States, Sweden, Spain and Russia.
Separately, 90 jobs are being created with the opening of a TK Maxx shop in Dublin's Ilac Shopping Centre.