The Tigers had to show plenty of character and spirit to get the job done, coming from behind to lead 2-1 at half time thanks to goals from Jackson Irvine and Fraizer Campbell.
Irvine added his second and his side’s third of the night shortly after the break and although Jamie Proctor pulled one back for the Millers to make it a nervy finish, Nigel Adkins’ men dug in to see the job through.
Reece Burke returned from a minor injury problem as one of two changes to the side that lost to Blackburn Rovers at the weekend. Daniel Batty also came back into the side, with Stephen Kingsley and Angus MacDonald both missing out. Jon Toral, who came on from the bench at the weekend, is also absent.
The Tigers made a bright start, enjoying plenty of possession inside the Rotherham half with Fraizer Campbell flashing an early cross right through the Millers’ six-yard box.
Markus Henriksen had the first effort of note of the evening as his powerful 25-yard drive had to be pushed over the bar by Rotherham goalkeeper Marek Rodak. Batty’s effort from the resulting half-cleared Evandro corner brought an even better stop, with Burke then sending an effort just over as the visitors threatened to hit the front.
However, it was Rotherham who took the lead from a 16th-minute corner. An out-swinging delivery was met by Millers’ skipper Richard Wood and he headed into the bottom corner of the net.
Batty curled an effort just over from distance as the Tigers looked to respond, while Rotherham went close to a second through Ryan Manning’s shot that flew just wide.
The Tigers equalised in the 28th minute with a delightfully worked goal. Jarrod Bowen cut in from the right before slipping a pass forward for Campbell. He knocked it back for Evandro to deliver a first time cross to the far post for Irvine who volleyed home for 1-1.
Nigel Adkins’ side were inches away from finding the killer pass to set up goal number two as the clock ticked down towards half time, but as the half moved into added time that golden ball did arrive. Eric Lichaj supplied it with a low ball in from the left and Campbell was there to apply the finish.
Henriksen picked up a yellow early in the second half after a strong challenge on Matt Palmer, and it wasn’t the only strength on show as the Tigers made it 3-1 just two minutes into the half. Really strong play from Campbell saw him take possession from centre back Semi Ajayi out wide before a clever ball sent Bowen into the box. He was unselfish as he squared for Irvine to slot home his second of the evening and give his side some breathing space.
Campbell drove a 25-yarder wide as the visitors threatened to hit their opponents on the break, with David Marshall making a comfortable save from Michael Smith at the other end.
Wood should have brought his side back into it when left unmarked to meet a 67th-minute corner but he could only head wide, before a first Tigers change saw Will Keane replace Campbell.
Bowen and Keane were both denied by near-post saved from Rodak, with Irvine then firing a hat-trick chance just over the bar from ten yards.
Rotherham pulled a goal back with 15 minutes remaining as they kept the ball alive well before a cross from the right wing was headed in by substitute Proctor.
A second change from the Tigers brought Kevin Stewart on for Batty while a third saw youngster Robbie McKenzie replace Evandro.
Rotherham threw plenty of high balls forward in the closing stages with Ajayi heading a good chance wide and Marshall making a routine save from Will Vaulks as the Tigers held on through five minutes of added time to see out an important win.
Rotherham United: Marek Rodak, Zak Vyner, Joe Mattock, Will Vaulks, Semi Ajayi, Richard Wood, Matt Palmer (Jamie Proctor 73), Jon Taylor (Kyle Vassell 56), Ryan Manning, Ryan Williams (Joe Newell 56), Michael Smith.
Subs Not Used: Laurence Bilboe, David Ball, Clark Robertson, Sean Raggett.
Hull City: David Marshall, Todd Kane, Reece Burke, Jordy de Wijs, Eric Lichaj, Markus Henriksen, Dan Batty (Kevin Stewart 77), Jarrod Bowen, Evandro (Robbie McKenzie 79), Jackson Irvine, Fraizer Campbell (Will Keane 67).
Subs Not Used: George Long, Nouha Dicko, David Milinkovic, Adam Curry.
Referee: Mr J. Simpson.
Attendance: 8,962 (1,225 Visiting Supporters).