The Black Cats fell behind in the 13th minute when Luke Cundle’s effort deflected off Luke O’Nien and past goalkeeper Anthony Patterson.
It was a tough first half for Tony Mowbray’s side as the hosts dominated possession and doubled their lead through Harry Darling on the stroke of half-time.
Sunderland pulled a goal back through Jack Clarke at the start of the second half but couldn’t salvage a point.
Our Sunderland writer Phil Smith has dished out his player ratings from the Swansea.com Stadium:
1. Anthony Patterson - 7
Perhaps could have done better with Swansea’s goal but the scoreline would have been worse if not for a number of really strong stops from the Sunderland goalkeeper. Made another couple of terrific saves on his line from set plays. 7 Photo: Martin Swinney
2. Lynden Gooch - 5
Had a very difficult first half as Swansea built some really good moves down his flank - stepped up big time in the second half and was much, much improved. 5 Photo: Frank Reid
3. Luke O’Nien - 6
Unfortunate to play a big part in the opening goal, he made some big interventions in the second half that prevented the hosts landing a knockout blow on the break. 6 Photo: Frank Reid
4. Danny Batth - 6
Another solid enough showing from the experienced defender, who was left exposed too often by the players around him through the first half. 6 Photo: Frank Reid