Intercom is to create 100 highly-skilled software engineering and design jobs in Dublin over the next 18 months.
The early stage technology start-up company was founded by four young Irish men.
The expansion follows a substantial $23 million (€17m) investment in the two-year-old company by two US venture capital funds, including Bessemer Venture Partners.
Bessemer is a veteran technology investor, which was an early stage funder of several successful technology companies, including Skype and LinkedIn.
Intercom would not divulge what it is now worth following the fresh investment.
However, based on previous similar-sized investments in companies of a similar scale, it is estimated Intercom may be worth close to $100m (€74m).
The company is developing a personal messaging service for web and mobile businesses to allow their customers to interact with each other.
The company has secured nearly 2,000 customers, including Yahoo, Rackspace and Visual.ly, since it began operating.
Intercom said it is not yet profitable, but is not trying to be at present, as it is putting all its resources into developing the product.
The company currently employs 47 staff, more than 30 of whom are working on engineering and developing the product in Dublin.
The remainder are based in San Francisco and elsewhere, where they are carrying out leadership, marketing and finance functions.
The company was formed in late 2011 and previously raised $6m (€4.4m) in Series A funding from investors led by The Social+Capital Partnership, the firm founded by former Facebook vice president Chamath Palihapitiya.
Prior to that, it also raised $1m (€737,000) in seed funding from a range of other investors.
Intercom has also recruited former PayPal and Yammer executive Mark Woolway as chief operating officer.