The Black Cats were beaten 5-1 at the New York Stadium as Aiden McGeady was sent off for the visitors.
Rotherham opened the scoring in the 10th minute when Michael Smith headed home Freddie Ladapo’s cross.
Sunderland managed to draw level before half-time, though, when Ross Stewart produced a neat finish from inside the area.
But it was all downhill from there for the visitors, as Freddie Ladapo made it 2-1 before half-time.
McGeady was sent off shortly after the interval, before Smith and Ladapo both added another goal each to their names, while defender Michael Ihiekwe also got on the scoresheet.
Sunderland will hope to bounce back when they travel to Sheffield Wednesday on Tuesday.
Our chief Sunderland writer Phil Smith has delivered his verdict on how each player fared at the New York Stadium:
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9. Aiden McGeady - 3
Was a threat on the ball in the first half and played a part in the first goal, but hard to comprehend his wild challenge when his side were two goals down and he already had a yellow. The game was drifting but from that moment it was well and truly gone. 3 Photo: JPI Media
10. Elliot Embleton - 5
Probably unfortunate to be hooked at the break, more a reflection of the desire to change system. Couldn’t get into the game much given Rotherham’s dominance but did play one or two good passes. 5 Photo: JPI Media
11. Ross Stewart - 6
Kept his side in the game with an excellent first-half performance, scoring one fine goal and coming within inches of another. Had no service in the second half. Just about the only Sunderland player to get close to the required level. 6 Photo: JPI Media
12. Bailey Wright (sub) - 3
Brought on to try and shore it up, but was beaten far too easily by Smith for the fourth. Struggled throughout the half. 3 Photo: JPI Media