After a goalless first half Ross Stewart scored twice after the interval following two crosses from Jack Clarke.
Clarke then got on the scoresheet after an excellent run and finish, before he was substituted to a standing ovation.
The result means Sunderland have taken 11 points from their first seven league games this season.
Our chief Sunderland writer Phil Smith has dished out his player ratings from the Stadium of Light:
9. Patrick Roberts - 7
Was left frustrated in the first half as his team mates struggled to find him in areas where he could really do damage. Unsurprisingly looked a massive threat in the second half as his team lifted it. Came off with what looked like a muscle injury, which is a big concern for Sunderland. 7 Photo: Frank Reid
10. Jack Clarke - 8
A top performance. Played his part in the first goal and Rotherham couldn’t really get near him on the ball. Finding his groove and that is good news for Sunderland. 8 Photo: Chris Fryatt
11. Bradley Dack - 6
Couldn’t impact the game in the first half and is clearly still building his match sharpness, but showed his class with a delicate assist for Jobe’s second. 6 Photo: Frank Reid
12. Alex Pritchard (sub) - 6
Not as influential as in recent weeks, but played some smart passes as Sunderland saw the game out with relative ease. 6 Photo: Frank Reid