The result should give Pools a boost a week ahead of their FA Cup fourth round clash at home to Premier League West Ham.
Hartlepool took the lead on five minutes but the promise that early goal gave of an entertaining game didn't materialise.
The goal came when Porter exchanged passes with Michael Mackay and found himself unmarked right in front of goal.
He finished well with a low 15-yard shot for his 14th goal of the season.
But while Mackay twice went close with curling shots from the edge of the area, the first well saved by Chris Dunn and the second just off target, Hartlepool couldn't add to their lead.
Northampton battled to come back but created nothing until Adebayo Akinfenwa looped a shot from the edge of the area just over the bar on 35 minutes.
The second half started as tamely as the first had finished but Porter brought the game alight for a second time when he doubled the home lead on 56 minutes.
Andy Monkhouse ran at the Town rearguard from his own half and his defence-splitting pass gave Porter the chance to collect the ball and finish well from 15 yards.
The game was won but Northampton did have plenty of possession in the last half-hour, only to run into a hard-working defence determined to keep a clean sheet.
Northampton's contribution to the game was a poor one, with Porter's finishing the shining light in a scruffy match littered with mistakes.