Lewis Wing's late free kick prevented Rovers from taking all three points as Rotherham United picked up a precious point in their battle to avoid relegation.
Wing thumped home from 20 yards with just four minutes remaining to punish Rovers for not taking their opportunities throughout the contest.
The chances were there for Rovers after Adam Armstrong's 26th goal of the season put the visitors in front.
Armstrong, Joe Rothwell, Bradley Johnson and Ben Brereton missed the best opportunities to kill off any threat of a Millers comeback before Wing struck.
There were to be a couple of more opportunities later on though, but Blackman pulled off a fine stop to deny Armstrong from adding to his tally and scoring what would have been a winning goal.
Johnson was the only change to the starting XI from the 5-2 win over Huddersfield Town a week earlier.
He slotting into midfield in place of Corry Evans to chalk up his 50th league start for the club.
The hosts were quickest out of the blocks with Darragh Lenihan getting a crucial block on Freddie Ladapo's snapshot inside the opening minute at the New York Stadium.
Soon after and Jamie Lindsay let fly from the edge of the box and saw his shot whistle just past Thomas Kaminski's left-hand post.
However, Rovers took the lead with their first attempt on target and it came from that man Armstrong.
Amari'i Bell hooked a high ball in the air, Angus MacDonald didn't deal with it well enough, Armstrong robbed him and then calmly slotted past Jamal Blackman for his 26th goal of the season on 17 minutes.
Armstrong almost bagged his and Rovers' second of the day five minutes later, but Blackman was out quickly to get the block in and deny the top goalscorer.
The goal knocked the stuffing out of a Millers side who struggled to create too much in the first-half, although Chiedozie Ogbene nodded Ryan Giles' left wing cross wide just after the half hour mark.
Rotherham had to respond at the beginning of the second-half, but it was Rovers who went close to adding to their tally when the returning Johnson powered a header towards goal, but Blackman stuck out a left paw to claw away what would have been a certain goal.
From the resulting corner, Darragh Lenihan saw his glancing header drift across goal with nobody there to tap home.
At the other end, Ogbene lashed across goal as the Millers looked to keep Kaminski busy before Joe Rothwell hit across goal and wide from a narrow angle.
Rovers were punished for not taking the opportunities with four minutes remaining through as Wing thumped home a late equaliser.
Things could have got worse a moment later when George Hirst saw his header tipped behind by Kaminski before the Belgian blocked the same player from the resulting corner.
Rovers could have won it when they charged straight up the other end, but Giles did superbly to flick Lewis Travis' cross away from the lurking Armstrong, who was certain to score.
The next chance fell to Armstrong a minute later, but he saw Blackman in his way after he latched onto Harvey Elliott's superb pass through.
That was to be that as the full-time whistle was blown as Rovers were forced to rue missed chances once more.
Rotherham United: Blackman, McDonald (Wiles, 46), Wing, Wood (c), Ladapo, Ogbene (Jozefzoon, 69), Lindsay (Barlaser, 69), Ihiekwe, MacDonald (Harding, 36), Smith (Hirst, 69), Giles.
Unused substitutes: Vickers, Mattock, Sadlier, Olusunde.
Goal: Wing, 86.
Booked: Smith, 21, Lindsay, 68, Barlaser, 79.
Rovers: Kaminski, Nyambe, Lenihan (c), Harwood-Bellis, Bell, Travis, Johnson, Rothwell (Elliott, 83), Gallagher (Dolan, 73), Brereton, Armstrong.
Unused substitutes: Pears, Douglas, Davenport, Buckley, Evans, Bennett.
Goal: Armstrong, 17.
Referee: Tony Harrington.