After a bit of a shaky start, the Black Cats took a two-goal lead before half- time after a Terrell Thomas own goal and Ross Stewart header.
Stewart added his second goal of the match from a corner after the break, before substitute Leon Dajaku added a fourth.
The result means Sunderland have won nine of their first 12 league games this season, ahead of a home game with Charlton this weekend.
There was another positive as winger Aiden McGeady returned to the starting XI and played 75 minutes after missing two league games with a foot issue.
The result means Sunderland have moved up to second in League One.
Our chief SAFC writer Phil Smith has delivered his verdict on how each player fared at the Mornflake Stadium following an impressive win for the Black Cats.
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1. Thorben Hoffmann - 7
Distribution was a little slack early on but improved considerably. One or two uncertain moments claiming crosses but produced yet another stunning reflex save to defy Mandron. That was quality well above the level. 7 Photo: JPI Media
2. Carl Winchester - 8
Terrific defensive display. Made some key challenges, rarely beaten and got forward when he could. Barely put a foot wrong. 8 Photo: JPI Media
3. Tom Flanagan - 7
Another steady defensive showing from Flanagan, who cleared set pieces well and snuffed out danger. Unlucky not to get an early goal. 7 Photo: JPI Media
4. Callum Doyle - 7
Defensively sound and his distribution was very good for the most part. Carried the ball out well then the opportunity presented. 7 Photo: Frank Reid