The 23-year-old USA international striker arrived at the Stadium of Light from AZ Alkmaar on Tuesday on a four-year deal.
"I'm excited," Altidore told Sunderland's official website. "It's a fantastic club, everyone here is so welcoming. I'm really excited about this season - it has everything here, all the combinations to be a big club, so I'm really excited to be a part of it."
The Black Cats start the new campaign at home to Fulham on August 17.