Jason Crowe should have given the Cobblers an early lead when he exchanged passes with Akinfenwa but Terriers goalkeeper Alex Smithies was able to tip his shot past the post.
Northampton goalkeeper Chris Dunn then saved well from the dangerous Danny Cadamarteri while Ryan Gilligan cleared off the line from Phil Jevons, who also hit a first-time shot just wide as the Terriers created the better chances in the first half.
Jevons eventually opened the scoring for Huddersfield in the 65th minute when he curled a superb 25-yard free-kick around the wall and into the corner of the net to register his first goal of the season.
The home side's task was made more difficult in the 75th minute when Crowe was shown a straight red card - his second dismissal of the season - for a trip on Gary Roberts, who was clean through.
But Akinfenwa drove home the equaliser from the edge of the box in the third minute of stoppage time.