The 33-year-old won his first international cap against New Zealand in November 2005 and he has gone on to play 89 times for Ireland, making him his country's most-capped hooker. He has scored eight tries in the green jersey.
Best started every game of Ireland's 2014 and 2015 successful RBS 6 Nations Championship campaigns as well as featuring in all but one of Ireland's matches at the 2015 Rugby World Cup.
Commenting on his new contract, Best said:
"I am very happy to have signed a two year Irish contract to remain with Ulster Rugby. It is a great honour to play for Ulster and Ireland and I am privileged to have the opportunity to captain this talented group of Ulster players. Our challenge now is to deliver on the promise we have shown and reward our fans with strong performances."
Ulster's Director of Rugby, Les Kiss, was equally delighted with the news:
"I have worked closely with Rory for a number of years in the national set up and the quality he delivers so consistently reflects his character and his talent. His leadership, tenacity and drive are incredibly important to what we are looking to achieve at Ulster Rugby."
IRFU, Performance Director, David Nucifora, added:
"Rory contributes so much to Irish rugby both on and off the field. He is a model professional who has consistently performed at the top level for both club and country. We are delighted to have secured his services for a further two years."
