Steve Evans' side, promoted from the fourth tier last season, made it 15 league games unbeaten as the club ended a 26-year wait for a victory at Gillingham on Saturday.
And they could scarcely have done it in more dramatic fashion, Tom Hitchcock scoring twice in the final four minutes to complete his hat-trick and wrap up a superb comeback.
A top-two finish is still within Rotherham's reach but leaders Wolves and second-placed Brentford both won to keep the chasing pack at bay.
Wolves ran out comfortable 2-0 winners at home to play-off-chasing Peterborough United and Kenny Jackett's charges are closing in on an immediate return to the Championship.
Brentford capitalised on Haydn Hollis' first-half dismissal to beat Notts County 3-1, with Alan Judge scoring twice to end the visitors' three-match winning run and leave them second from bottom.
Fifth-placed Preston North End, who are now also assured of a top-six finish, were held to a 1-1 draw at Bristol City.
Shrewsbury Town were the big winners at the other end of the table as Jon Taylor scored the only goal of the game against rock-bottom Stevenage, who could not find a way back despite Asa Hall's late red card.
There were two sides playing in Colchester United kits at the Colchester Community Stadium, where Tranmere Rovers were forced to wear the hosts' changed strip after the referee refused to allow them to wear their sky blue away kit.
It mattered little to Rovers - though the club did announce on Twitter their intention to complain about the decision - as the visitors boosted their survival hopes with a 2-1 success.
Gary Madine's first goal since returning to former club Carlisle United on loan earned the relegation strugglers a 1-0 over Swindon Town, while Port Vale beat Walsall by the same margin.
Elsewhere, Oldham Athletic won 3-2 at Bradford City, Leyton Orient were held to a 1-1 draw at Sheffield United, Milton Keynes Dons prevailed 2-1 at Coventry City, and Crawley Town lost 2-1 at home to Crewe Alexandra.
