The popular Taylor had seen his side take a 63rd minute lead through an Andy Holt header and the Cobblers looked to be heading for a comfortable success until Mirfin glanced home a 75th minute equaliser to earn the Terriers a point.
Northampton should have taken all three points after having the best of the game for long periods, particularly in the first half when they created several good openings.
Chris Doig was just off target with a far-post header, Bradley Johnson went close to catching out keeper Matt Glennon with a crafty chip and Danny May saw a goal-bound effort deflected wide as Northampton made all the earlier running.
The best chance of the half fell to Simon Cox in the 25th minute after he raced on to a through ball, beat the offside trap and Glennon, only to see his shot hacked away by defender Martin McIntosh.
Huddersfield rarely threatened but striker Luke Beckett had a couple of half chances late on, seeing a chip go just wide and then a snap shot missed the target.
Adnan Ahmed went close with a first-time volley from the edge of the box and then saw a deflected effort scrape the bar after Frank Sinclair pulled the ball back.
Taylor came off to a standing ovation after 61 minutes and two minutes later Northampton took the lead, when his replacement David Hunt produced a long throw-in which Holt headed home off the underside of the bar.
Glennon kept Huddersfield in the game when he produced a smart save to deny Johnson after a neat through pass from Hunt and Huddersfield grabbed a point in the 75th minute.
Northampton failed to clear a cross and when John McAliskey turned the ball back into the box, Mirfin glanced home a header via the far upright.
Substitute Lucas Akins almost grabbed an unlikely winner for Huddersfield in stoppage time, but he placed his header just wide of the far post.