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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1. Thorben Hoffmann - 4
Not much he could do about many of the goals, though was caught in possession for the fifth. Struggled to command his box but the whole defence was ultimately overwhelmed. 4 Photo: JPI Media
2. Carl Winchester - 5
Didn’t get anywhere near enough help through a challenging start to the game. Offered energy and tenacity in midfield through the second half but had little chance of making an impact when his side went down to ten. 5 Photo: JPI Media
3. Tom Flanagan - 4
Was left frustrated with those in front of him through the opening exchanges, trying to organise his side with little result. Dealt with the challenge better than some of his team-mates but it was a wretched afternoon for the defence. 4 Photo: JPI Media
4. Callum Doyle - 4
His toughest afternoon in senior football by a distance. Did make some good challenges early in the second half but ultimately struggled to deal with the Rotherham front line and erred too often in possession. 4 Photo: Frank Reid