All seemed to be going well for the visitors when Tom Barkhuizen expertly fired them into a 13th-minute lead, but Rovers battled back admirably through Elliott Bennett's 30-yard piledriver in the 43rd minute and Craig Conway's composed effort 13 minutes later.
However, Simon Grayson's men, who started the day six points away from the play-offs, grabbed a leveller they scarcely deserved on the balance of play through McGeady's cool finish from 12 yards.
It was harsh on Rovers, who stretched their unbeaten run under head coach Tony Mowbray to seven games. They do, however, remain in the drop zone.
Preston's winless run away from home now stands at seven games but they are within two wins of climbing into the top six, as things stand.
Grayson named an unchanged side after the comprehensive defeat of Reading, while Blackburn handed a first start to Lucas Joao with Charlie Mulgrew returning after injury.
The Lilywhites had the first chance and hit the front in the 13th minute thanks to a superb one-two between Barkhuizen and Jordan Hugill, the latter cushioning the perfect pass for the former to control and stab home his fifth Preston goal from six yards.
McGeady lashed a thunderous volley over moments later as Grayson's men sought to hammer home their advantage.
At the other end, the in-form Joao was central to all of Blackburn's best moments. First, he engineered space at the edge of the area but blazed over and then met a Derrick Williams cross but saw his header crash off a post.
Rovers got the goal their endeavour deserved two minutes before half-time when Bennett received the ball 30 yards out and let fly with a sensational strike that arrowed into the bottom left corner.
Preston regrouped at the break and had two early chances but Barkhuizen could not control a half-volley from Daryl Horgan's cross.
Then, McGeady's delightful 50th-minute ball evaded everybody in the six-yard box, when any touch would do.
And Rovers made them pay in clinical fashion in the 56th minute as Marvin Emnes controlled and produced the perfect pass for Conway, who kept his composure to slide home from 12 yards for his sixth goal this term.
Mowbray's team were in full flow by this point and youngster Ryan Nyambe almost got a third midway through the half after twisting and turning on the right, but his fierce drive whistled wide.
Substitute Paul Gallagher saw a late effort saved and just when it looked like the hosts would prevail, Tom Clarke found McGeady 12 yards out in the third minute of stoppage time.
He showed nerves of steel to slot in his fifth for Preston, thus snatching an unlikely point.