A header from skipper Johnny Mullins separated Rotherham and rivals Chesterfield in the derby at the New York Stadium.
The Millers were far and away the more dominant team and never looked like taking anything less than all three points from an out-of-sorts Spireites side.
Sam Togwell had a goal ruled out for offside and Armand Gnanduillet was inches away from giving the visitors an unlikely point deep into injury time.
It was the fifth consecutive game on the road that Paul Cook’s men have failed to win in a run of form that leaves them eight points adrift of the League Two play-offs.
Cook started with both Jack Lester and Marc Richards in a 4-4-2 formation that would have been music to the ears to some Spireites fans.
And it was the visitors, backed by a vocal 2,338 away support, who had the first effort of the afternoon through Lester.
The experienced striker, on his first start since New Year’s Day, charged forward unchallenged from midway through his own half. But his shot from the edge of the penalty area lacked power and direction and was comfortable for home keeper Andy Warrington.
Rotherham almost went one better moments later when Daniel Nardiello’s 20-yard effort had Tommy Lee beaten diving to his right and smacked the outside of the post.
Nardiello was inches away from connecting with Alex Revell’s right-wing cross as the hosts began to find holes in Chesterfield’s back-line.
Warrington was on hand to make a crucial reflex save after a coming together of Claude Davis and Richards threatened to present the visitors with an early lead in a blistering opening 20 minutes.
The home support were up in arms when they believed the ball had struck Neal Trotman’s hand just inside the penalty area, but both the referee and the near-sided linesman waved away their appeals.
The Millers’ striking duo of Nardiello and Revell combined again and the latter this time was a fraction away from getting a toe to the former Manchester United trainee’s delivery. Daniel Kearns picked up the loose ball and found David Noble 18 yards from goal, but his driven effort was deflected wide with a grateful Lee looking on.
In a rare flurry forward for the Spireites, Richards judged the flight of the ball better than his marker and fired a shot into the side netting from a tight angle.
Nardiello forced Lee into making a smart save from range before Togwell made a vital interception to deny Curtis Davis.
And it was Lester, so used to being Chesterfield’s saviour at the other end of the field, who prevented Kari Arnason from putting the hosts in front after Lee failed to hold a David Noble corner.
Then it was the turn of Liam Cooper, who had been booked for a crunching tackle on Revell minutes before, to clear Mark Bradley’s goal-bound header from danger as the half drew to a close.
The pattern of play was to continue early in the second half when Revell missed a golden opportunity after he was put through by Lee Frecklington. The striker screwed his effort wide with Neal Trotman closing in.
Chesterfield were noticeably rocked and even the simplest of passes were beginning to go astray. Nardiello - like his strike partner before him - was guilty of missing a glorious chance from eight yards.
But Rotherham were rewarded for their persistence when Noble’s right-wing corner was powerfully met by captain Mullins to head his side into the lead just before the hour.
The goal spurred the Spireites into action and Togwell fired wide with the goal gaping after Lester had chested down Nathan Smith’s ball forward.
Cook reacted by making a double-switch with Armand Gnanduillet and Conor Townsend replacing Lester and the ineffective Jay O’Shea as Chesterfield tried desperately to get back into the match.
Richards blazed high and wide from the angle and Gnanduillet headed over from Drew Talbot’s telling centre.
The Ivorian made a notable difference in attack and it was from his nod down that Togwell pounced, only for the linesman’s flag to cut the celebrations short.
Arnason drove one high over the bar as the clock reached the 90, but there was still time for the Spireites to give the hosts a late scare.
Townsend saw an in-swinging cross bounce the wrong side of the far post through a sea of players before another inviting delivery had Gnanduillet at full stretch but the striker was unable to connect to have rescued a point for the visitors.
Spireites (4-4-2): Lee; Talbot, Cooper, Trotman, Smith; Whitaker (Brindley 70), Hird (c), Togwell, O’Shea (Gnanduillet 60), Richards, Lester (Townsend 60)
Subs not used: Barrington, Randall, Wafula, Clay
Millers (4-4-2): Warrington; Bradley, Mullins (c), Davis, Ridehalgh, Frecklington, Arnason, Noble, Kearns (Cameron 90), Nardiello (Slew 85), Revell (Odejayi 83)
Subs not used: Thompson, Tonge, Pringle, Agard
Referee: P. Tierney
Attendance: 11,143 (2,338)