Despite the scoreline, Sunderland dominated possession from the off and full-back Ahmed Elmohamady had the first decent chance in the 14th minute with a header he glanced just wide from Phil Bardsley's cross.
Eidur Gudjohnsen then shot over for the visitors before Sunderland's Steed Malbranque charged down an attempted Philippe Senderos clearance only to clip a shot well wide.
The hosts went behind in the 33rd minute when Kakuta took advantage of some poor defending. The 19-year-old was picked out by Bobby Zamora and he poked the ball through the legs of Simon Mignolet.
Sunderland should have responded immediately but Lee Cattermole's finish was weak, while Sulley Muntari saw an effort deflected just over the crossbar.
The Cottagers doubled their advantage in the 61st minute with a goal from Davies that was as simple as it was clinical.
Steve Sidwell chased a long ball to the byline and cut it back for Davies to guide his shot into the far corner.
And it was game over in the 73rd minute as Mignolet and Anton Ferdinand got in each other's way as they attempted to clear Zamora's cross and Davies turned the loose ball home, despite the best efforts of Elmohamady.