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:
9. Patrick Roberts - 5
Sunderland were overwhelmed down their right flank through the first half and though Roberts did occasionally break into some decent areas, there was never a viable target for him to find in the box. 5 Photo: Martin Swinney
10. Elliot Embleton - 5
Summed up Sunderland’s afternoon - looked well off the pace in the first half and then was superb just after, playing a big part in the first goal. 5 Photo: Frank Reid
11. Jack Clarke - 7
Changed the game when he moved through the middle, scoring a good goal and finally giving his side a focal point to work off. Will give Tony Mowbray something to think about while his strikers are injured. 7 Photo: Martin Swinney
12. Jewison Bennette (sub) - 5
Has real ability on the ball but wasn’t able to show that in any advanced areas here. 5 Photo: Frank Reid