Pompey made it eight wins from their last 10 matches to stay in the play-off places heading into 2018.
The home side could have taken the lead after just six minutes when Hawkins was played in by Brett Pitman but visiting goalkeeper Matt Ingram was quick off his line to make the save.
Northampton then surprised the hosts when they went ahead in the 36th minute through Chris Long, who calmly slotted the ball past Luke McGee.
But Pompey hit back moments later through Matty Kennedy when he cut in from the left wing to drill a right-footed shot into the bottom corner.
Portsmouth then took the lead on the stroke of half-time when Hawkins headed Christian Burgess’ cross over Ingram’s head.
Hawkins got his second of the match to seal the points, arriving at the back post to nod in a Kennedy cross.
Burton midfielder Martin Samuelsen will use the international break to recover from illness after pulling out of Norway U21's games.
Jonas Lossl is staying 'optimistic' over Huddersfield's chances of survival this season and has urged his team-mates to 'go for it'.