Republic of Ireland winger McGeady joins from Everton on a three-year deal and, given how he impressed for Preston in the Championship last season, will offer Sunderland fans hope of an immediate return to the Premier League.
McGeady worked with new boss Simon Grayson during his loan spell at Deepdale, and the manager told his club's official website: "Aiden's career speaks volumes. He's been an exceptional player and was an outstanding performer at Preston last season."
The former Celtic and Spartak Moscow man is joined on Wearside by former Everton striker Vaughan.
He scored 24 goals in 37 appearances for Bury last season and has been widely considered to be better than League One standard.