9:36AM BST 08 Jul 2011
The 28-year-old Wales international became Steve Bruce's ninth summer signing when he followed Wes Brown and John O'Shea into the Wearside club in a busy 24 hours.
Vaughan was a key figure in the Blackpool's climb into the Premier League, but left within hours of sidekick Charlie Adam, who joined Liverpool yesterday, after rejecting an extended stay at Bloomfield Road.
Bruce said: "David was excellent throughout last season, including both games against us, so it's only natural that he caught the attention of a number of top clubs.
"We are delighted that he sees his future at Sunderland. His experience, grit and energy in midfield will be valuable assets to us and we are now looking forward to him joining up with the squad for pre-season training."
Vaughan began his career as a trainee at Crewe and after a spell in Spain with Real Sociedad, joined Blackpool for £200,000 three years ago.