The money will to used for the development of mobile software in the firm's healthcare division.
Kainos has a software platform called Evolve which is used for the storage of patient records and the integration of healthcare data.
The money will also be used to support a global sales push, particularly in the United States.
Alastair Hamilton, the chief executive of Invest NI, said the grant would help drive economic growth and foster the development of skills.
In 2017, Kainos's revenues from Evolve were around £10m and its records management system was in use at 35 NHS Trusts.
Brendan Mooney, chief executive of Kainos said: "Our Evolve Integrated Care software will allow healthcare professionals to access, amend and store patient information as they undertake their work, all with the required degree of security to protect patient confidentiality."
Kainos employs about 1,000 people across its global operation and is one of the few Northern Ireland firms to be listed on the London stock exchange.
Kainos, the Belfast-based IT firm, has been awarded a £3.1m grant by Invest NI to support research and development.