City recovered from 2-0 down to earn a point in South Yorkshire, but were still left wondering how they had not claimed a maiden victory at the New York Stadium.
Soft goals from Izzy Brown and Greg Halford left the visitors with a mountain to climb and only 16 minutes to climb it by the time Tammy Abraham poached one back.
But Bobby Reid slid in at the far post to draw City level and Jamie Paterson was only inches away from a debut winner as his vicious shot struck the post in the final minute.
Lee Johnson named an unchanged side after a brilliant second-half display blew away Aston Villa at Ashton Gate last time out.
New signings Joel Ekstrand and Paterson were among the substitutes, while Gustav Engvall remains sidelined by a knee injury.
Both teams threatened an early opener even before Brown cashed in on a moment of hesitation in the City defence.
First Richard O’Donnell had to be alert to make a sharp reaction save from Dominic Ball’s volley, before Joe Bryan lashed wide from 20 yards.
But then, seemingly from nothing, City fell behind.
Brown chased a long ball forward more in hope than expectation, but as O’Donnell advanced to the edge of his penalty area, the Rotherham man nipped in front of Aden Flint and ran the ball into the unguarded net.
From that moment City were firmly in control of the first period and unlucky to trail at the interval.
Top scorer Abraham tried his luck with an instinctive backheel after Bryan’s deflected shot landed at his feet with his back to goal. It would have been a spectacular equaliser, but Lee Camp was in the right place to ensure he was not caught by surprise.
Flint was using his height to good effect in the Rotherham box, seemingly connecting with every City corner, but the hosts were always equal to the second ball.
There were also a number of openings for the visitors from distance, but Luke Freeman and Reid were both guilty of failing to hit the target.
The same pair combined to cause the Millers a greater degree of concern ten minutes before the break.
Great work from Freeman saw the midfielder jink past his man and pull the ball across goal for Reid, who should have scored but rather scuffed his effort.
After Rotherham cleared the initial danger, Reid tried his luck again before Gary O’Neil forced a save from Camp down by his near post as City continued to turn the screw.
Then Abraham was involved again, nodding wide from Scott Golbourne’s cross before remonstrating with the referee over an alleged push from Kelvin Wilson, who seemed to be all over the Chelsea loanee.
Perhaps the closeness of Abraham’s header persuaded Andy Madley that the striker could not have been suitably impeded to award a penalty.
City’s best chance of the half arrived right at the end. Mark Little escaped down the right and crossed for Reid, who connected sweetly on the half-volley only for Camp to pull off an outstanding stop diving to his left.
The game would follow a similar pattern after half-time, as City resumed the action in the ascendancy but unable to make the breakthrough.
Reid and Abraham, City’s most likely suspects, both forced saves from Camp before another disastrous goal doubled the home side’s advantage.
There seemed no obvious danger when Halford’s tame shot looked destined for the arms of O’Donnell, but Flint was not to know and inadvertently deflected the ball past his own keeper in trying to clear the danger.
Johnson’s response was to make a triple substitution, including debuts for Ekstrand and Paterson as City switched to a 3-4-2-1 formation.
Also introduced was Callum O’Dowda, with Little, Golbourne and Freeman the men sacrificed.
City were always running a risk from then on, but had little choice. At one point Danny Ward raced through and blazed over when he probably could have put the game to bed, before Abraham poached his team a lifeline.
When Tomlin’s low shot bounced around in the Rotherham box, City’s teenage marksman reacted quickest to stab home from close range.
Camp had been guilty of failing to return the ball to City having finally been beaten, and Johnson took matters into his own hands soon after, charging down the touchline to retrieve a loose ball that had run beyond the byeline in a bid to speed up the game.
City’s intentions to keep playing were clear, and the 708 travelling fans were rejoicing when Bryan’s low cross was perfectly threaded through a crowded penalty area for the onrushing Reid, who slid in at the back post to convert a deserved equaliser.
Still that was not the end of the action. Abraham’s sharp effort on the turn was blocked by the legs of Camp, who somehow survived a goalmouth scramble before Paterson struck the post with a brilliant strike worthy of a debut winner.