The 23-year-old arrived on Wearside yesterday to complete a medical and he today became manager Paolo Di Canio's sixth signing of the summer.
A statement published on Sunderland's official website, www.safc.com, read: 'Sunderland AFC have confirmed the signing of US striker Jozy Altidore from Dutch side AZ Alkmaar.'
Altidore began his career with Major League Soccer side New York Red Bulls before joining Villarreal in 2008.
|Jozy in action USMT
He spent time on loan at Xerez, Besiktas and Hull - scoring one league goal as the Tigers headed for relegation from the Premier League in the 2009-10 season.
The striker agreed a permanent move to AZ in July 2011 and finished his first campaign in Holland with a haul of 22 goals in all competitions before adding 23 goals for the 2012-13 Eredivisie season, helping the club to a first KNVB Cup in 31 years.
Altidore has also scored 17 goals in 60 appearances for his country after making his senior debut in 2007. Having failed to score since November 2011, he ended a lengthy goal drought in an international friendly victory over Germany in Washington DC last month.
He joins goalkeeper Vito Mannone, defenders Valentin Roberge and Modibo Diakite, midfielder Cabral and winger David Moberg Karlsson as part of Di Canio's new-look squad at the Stadium of Light and the club confirmed he is expected to join his new team-mates at their training camp in Italy.