Rotherham manager Matt Taylor said securing Championship survival was no more than his team deserved and was made all the “sweeter” by their recent history in the division.
The Millers ensured they cannot be caught by Reading in the third and final relegation spot after beating promotion-chasing Middlesbrough 1-0 at New York Stadium.
Boro were reduced to 10 men just before the break when Anfernee Dijksteel was sent off and Rotherham took advantage at the start of the second half when Hakeem Odoffin fired home the only goal of the game.
The victory meant Rotherham staved off what could have been a fourth successive relegation from the second tier and ends a yo-yoing six-year period for the club between the Championship and League One.
A delighted Taylor, whose side go to rock-bottom Wigan in their final game, said: “What has been before for this club makes this moment sweeter. It’s fully deserved. I don’t know how much more this league can throw at us.
“There is one thing running through this club and that is spirit.
“Even had it gone down to the final game of the season I would have been confident. We are going to be better equipped next season. It’s a big achievement for the club.”
The two key moments of the match came either side of half-time, first with Boro losing Dijksteel in first-half stoppage time when the defender clumsily brought down Jordan Hugill on his route to goal and was given a straight red card.
Then, three minutes after the interval, Rotherham went ahead when Odoffin smashed a low shot beyond Zach Steffen from the edge of the box.
That proved to be the winning goal, although there were some nervy moments for the Millers, with Tommy Smith lashing over at the back post and Viktor Johansson pulling off a despairing save from a deflected effort by Jamie Lindsay.
Taylor said of the two main incidents: “Whether it was a sending-off not, I don’t know, but it felt it at the time.
“It was one moment of quality from Hakeem and time stood still before it hit the back of the net.
“Forty-nine points is a good tally with what has been thrown at us. I won’t be seeing the players for the next couple of days.”
Middlesbrough had already secured a play-off place, but defeat in South Yorkshire means they can no longer catch Luton in third and must settle for fourth spot.
Head coach Michael Carrick said: “I have mixed feelings. I am disappointed that we lost the game because that is definitely not what we came here to do. There are things to learn from it.
“I thought the first half for large parts suited them and not us. It was a bit stop-start and set-plays. There was not a lot of football played.
“The sending-off changes the game. It was a little bit harder to create that chance but I thought the boys did a lot of good things.
“I thought the red card was soft. Darragh (Lenihan) was covering him. It caught me by surprise when he got the red card out.
“If we had got that early goal it would changed the course of the game.”
