With Middlesbrough's defeat at Rotherham in the early kick-off having already guaranteed Town third place, the Hatters looked good for a 12th away win of the season as Tom Lockyer's header five minutes into the second half gave them the advantage.
But Blackburn levelled with an 86th-minute Hayden Carter header to ensure they can still make the top six by beating Millwall on the final day, and hoping that Sunderland and West Brom don't win their games at Preston and Swansea respectively.
The Hatters now know that finishing third means that the away play-off leg will kick-off at 5.30pm on Saturday 13th May, with the return at Kenilworth Road taking place at 8pm on Tuesday 16th.
Manager Rob Edwards made two changes with Luke Berry and Jordan Clark returning to the midfield in place of Pelly-Ruddock Mpanzu and Allan Campbell.
Clark has had to nurse his recent injury after an impressive first half to the season, it was his first start in a Hatters shirt since he signed his new contract in March.
His midfield partner Berry also made his first start since March, the number eight displaying a game-changing performance when we visited Ewood Park last season, scoring two late goals from off the bench.
Dan Potts and Fred Onyedinma were back from injury and returned to the bench.
The Hatters have already had their third place finish in the Championship confirmed before kick-off, as Middlesbrough have dropped points at Rotherham United earlier this afternoon.
Clark had the game's first chance, seizing on a loose pass across the halfway line by Ben Brereton Diaz and driving at the backpedalling Blackburn defence, keeper Aynsley Pears saving low as the midfielder got his shot off inside the box, having evaded a couple of challenges.
Harry Pickering spurned a glorious chance for Rovers after quarter-of-an-hour, firing wide from just inside the area, before Tom Lockyer headed an Alfie Doughty corner over the bar at the other end a couple of minutes later.
Amari'i Bell's pace and perfectly timed challenge denied Sammie Szmodics a shooting opportunity when Brereton Diaz slid him in through the middle.
Then Blackburn's sloppiness playing out from the back presented the Hatters with another chance on 25 minutes, Berry pouncing on Tyrhys Dolan's slip and mis-control to feed Carlton Morris for a shot that was deflected just wide, before the top scorer sliced a half-volley wide from Berry's knock-down a minute later.
Horvath saved well with his feet when Joe Rankin-Costello beat Doughty's challenge on the edge of the box and fred off a shot, but Town were soon asking questions at the other end again when Sonny Bradley met Cody Drameh's corner at the far post, nodding back across goal for Elijah Adebayo to head straight at Pears.
Bell's brilliant defending set up the Town's next attack in the 36th minute, the former Rovers defender nicking the ball off Rankin-Costello by his own corner flag before driving forward to trigger a move that ended with Doughty firing over from distance.
Dolan burst into the Hatters' box and fired across the face of Horvath's goal moments later, then Bradley did well to deflect the Rovers forward's shot away from the top corner with his head five minutes before the break.
Town started the second half on the front foot, Berry seeing a shot blocked as he looked to round off a wonderful passing move that went from inside the Hatters' half and across the pitch, with Clark and Doughty's sharp one-two off the left touchline eventually leading to Morris' cross for the midfielder.
They continued to press, and the opening goal came in the 50th minute, Morris crossing from the right angle of the area for Lockyer to steal in ahead of Bradley and head in his second goal in as many matches.
Morris and Clark combined to tee Adebayo up for a 58th-minute shot that Pears beat away, then Bell proved his worth once again at the other end, blocking Rankin-Costello's effort as the Blackburn midfielder looked at finish off a 64th-minute set-piece.
Town came as close as possible to extending their lead in the 73rd minute when Bradley's header came back off the crossbar after Morris had headed Drameh's deep free-kick back cross goal.
Bradley produced another timely block on 83 minutes, deflecting Szmodics attempted curler from the edge of the box wide, before getting his head on the resulting corner to help clear the danger.
Town's defence could no nothing moments later, however, when Carter met a corner with a firm header into the bottom corner for the equaliser.
Szmodics rattled the crossbar in injury-time as Rovers pressed for a winner, but a poine apiece was with end result meaning the Lancashire side need to win at Millwall on the final day to stand any chance of making the play-offs.
TOWN: Horvath, Drameh (Potts 83'), Lockyer, Bradley, Bell, Doughty (Onyedinma 66'), Nakamba (Campbell 74'), Clark (Mpanzu 66'), Berry, Morris (Freeman 75'), Adebayo.
Subs: Shea, Taylor.
Goal: Lockyer 50'
ROVERS: Pears, Rankin-Costello, Carter, Hyam, Pickering (Brittain 80'), Travis (Leonard 81'), Wharton, Hedges (Thomas 54'), Szmodics, Brereton Diaz, Dolan (Dack 54').
Subs: Hilton, Ayala, Garrett.
Goal: Carter 87'
Referee: Darren England
Att: 17,261 (1,101 Hatters)
