Midfielder completes deadline-day switch.
Kieran Richardson has completed a deadline-day move to Fulham for an undisclosed fee.
The 27-year-old, who was in his final year of his contract on Wearside, has returned to London after five years at the Stadium of Light.
He joined Sunderland from Manchester United in summer 2007, linking up with former United midfielder Roy Keane, then in charge of the Black Cats.
Richardson made 149 appearances for Sunderland, scoring 15 goals.