The defender, who marked his 100th cap for Ireland by scoring a stoppage time equaliser in Tuesday's 1-1 draw against world champions Germany in a Euro 2016 qualifier, moved to the north east from Manchester United in 2011.
"He is our captain, one of our leaders, and I am sure he will continue to help us get better and stronger as a team. I really look forward to continuing to work with John," coach Gus Poyet the club's website.
Sunderland are currently 13th in the standings with eight points from seven games and travel to Southampton on Saturday.
(Writing by Pritha Sarkar, editing by Ossian Shine)
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