The Black Cats were dealt a first-half blow when striker Ellis Simms limped off the pitch with an injury.
Yet two goals from Patrick Roberts in quick succession before the break put the visitors in a commanding position.
Jack Clarke then added a third in the 69th minute as Sunderland recorded their joint biggest win of the season.
Our Sunderland writer Phil Smith has dished out his player ratings from the Select Car Leasing Stadium:
1. Anthony Patterson - 7
Barely had a save to make but got through his work with little fuss and distribution was calm. 7 Photo: Martin Swinney
2. Luke O’Nien - 8
Made sensible decisions in possession and defended resolutely - admittedly against a surprisingly poor opponent. Has overcome a slow start to the season very well. 8 Photo: Frank Reid
3. Danny Batth - 8
Has been such a key part of Sunderland’s strong start to the season, showing he is still every bit a Championship player again. 8 Photo: Frank Reid
4. Aji Alese - 9
To say he took his chance was an understatement. Stepped out with the ball well and barely lost a duel. Looks a real find on this showing. 9 Photo: Frank Reid