Big boost for the Millers in survival mission ... on-the-whistle report: Rotherham United 2 Sunderland 1
Quality goals from Ollie Rathbone and Shane Ferguson either side of half-time put the Millers in the driving seat and they survived pressure after the Black Cats had forced their way back into the contest to hold on for the win.
The result, which came after two successive losses, moved Matt Taylor's men up to 20th in the table and increased the gap between them and the drop zone to five points.
AESSEAL New York Stadium erupted at the end, with supporters appreciating the significance of taking three points from a side who had arrived from Wearside in fifth spot.
Little had happened in the opening 19 minutes but that suddenly changed in spectacular fashion to the delight of the home crowd.
Tariqe Fosu made ground and played the ball into Rathbone who took a look and then fizzed a low 20-yarder into the South Stand net.
A minute later, there were heroics to match from Viktor Johansson at the end from as the keeper denied the visitors an instant response with a stunning save to tip away an Alex Prichard curler that was heading for the top corner.
Daniel Ballard headed the ensuing corner wide.
Rathbone is nursing a groin complaint but no-one would have guessed as he led the Millers charge on a mild February evening.
Johansson was out like lightning to avert the danger as Joe Gelhardt looked to scamper clear.
Rotherham should have been awarded a penalty but referee Chris Kavanagh missed a Dan Neil barge on Jordan Hugill as the striker looked to get on the end of a Rathbone cross.
The Millers were giving their all and supporters warmed to their efforts as they maintained their lead and looked to take the game to the Black Cats.
Clever touches from Fosu and silky play from Leo Hjelde brought roars of approval as the home side controlled proceedings up to the break.
There was a savage blow just before the interval, however, when Grant Hall stretched to control a long pass and had to leave the field with what looked like yet another hamstring injury for the centre-half.
Rotherham had made two changes to the team that had started Saturday's 2-0 home loss to Coventry City.
Fit-again Hjelde was back in the line-up following an ankle injury as Cohen Bramall dropped to the bench and Fosu returned at the expense of Hakeem Odoffin after being rested against the Sky Blues.
Rathbone tested Anthony Patterson with a low drive soon after the restart as the Millers continued to dominate.
Gelhardt had the ball in the net for Sunderland with a close-range volley from a right-wing cross but his effort was ruled out for offside.
And Rotherham took advantage of the let-off almost immediately as Fosu robbed Neil and played in Ferguson whose precision finish from just outside the box always had the beating of Patterson on its way into the bottom far corner.
Just six minutes later, however, Sunderland were back in the game when Gelhardt headed in Luke O'Nien's right-flank cross.
The visitors were now having a spell on top but the Millers, with Lee Peltier outstanding at the back, managed to hold out.
Conor Washington hit the post late on when a third goal would have brought much-needed relief and Johansson saved well to keep out Gelhardt's header.
In time added on, Johansson was the hero yet again, beating out Gelhardt's fierce shot.
Soon after came the final whistle. Cue joy at New York on a night when the outcome mattered so much.
Rotherham (4-3-3): Viktor Johansson; Lee Peltier (Hakeem Odoffin 79), Grant Hall (Wes Harding, 45), Cameron Humphreys, Leo Hjelde; Ollie Rathbone (Conor Washington 79), Conor Coventry, Tariqe Fosu; Chiedozie Ogbene, Jordan Hugill (Georgie Kelly 79), Shane Ferguson (Jamie Lindsay 64). Subs not used: Josh Vickers, Cohen Bramall.
Sunderland (4-4-2): Anthony Patterson; Luke O'Nien, Danny Batth (Trai Hume 63), Daniel Ballard, Dennis Cirkin (Aji Alese 63); Edouard Michut (Patrick Roberts 63), Amad Diallo, Dan Neil, Alex Pritchard (Jewison Bennette 85); Joe Gelhardt, Jack Clarke (Abdoullah Ba 85). Subs not used: Alex Bass, Pierre Ekwah.
Goals: Rathbone 19, Ferguson 55 (Rotherham); Gelhardt 61 (Sunderland).
Referee: Chris Kavanagh (Greater Manchester).
Attendance: 10,522 (2,190).