The 22-year-old former Derry City midfielder has been rewarded for his meteoric rise on Wearside just seven months after his £500,000 switch to the Black Cats on a three-year deal.
McClean said: "I'm thrilled to be here. I'm really enjoying my football and to have earned a new contract is a dream. I'm over the moon to see my next three years with Sunderland."
Manager Martin O'Neill added: "I'm absolutely delighted James has committed himself to the club. He's had an explosive start to his career here at Sunderland and long may it continue."