The agreement will result in significant investment for the game of rugby at all levels within the Province.
Kingspan, whose global headquarters are in Kingscourt, County Cavan, has been a sponsor of Ulster Rugby since 1999.
Commenting on the landmark deal, Chief Executive of Ulster Rugby, Shane Logan, said:
"We are delighted to have extended our partnership with Kingspan, one of Ulster 's most successful international companies, and to have secured a stadium naming rights partner for the first time.
"This is a landmark deal and one that will have considerable benefits for all of rugby in Ulster.
"I want to thank Kingspan for its long-term commitment to the Province and I look forward to many more special rugby occasions, from school and club finals to European match nights, at Kingspan Stadium in the future."
Pat Freeman, Managing Director of Kingspan Environmental said: "Both Ulster Rugby and Kingspan are successful globally recognised brands within their respective fields.
"We have been a partner of Ulster Rugby for 15 years and have witnessed the tremendous growth of rugby in the Province. We have also had extensive input into the redevelopment of the stadium through our high performance technologies. We are delighted to significantly extend our already strong association with Ulster Rugby by putting our name to such a wonderful sporting venue and are proud that the home of Ulster Rugby will be now known as Kingspan Stadium."
John Robinson, President, IRFU (Ulster Branch), warmly welcomed the new association when he said:
"This long-term deal, with a leading Ulster company, will result in a highly significant investment for rugby in the Province and is a contract of which all involved can be very proud. Rugby has never been stronger in Ulster and partnerships such as this will enable us to continue to grow the game at club and schools level and to remain competitive both in Europe and the PRO12."
Guinness PRO12
Suite 208, Alexandra House,
The Sweepstakes
Ballsbridge, Dublin 4, Ireland