The on-loan striker popped up in the first half to net the only goal of the game to earn the Cobblers a welcome home victory.
Hartlepool began the brightest with their neat football and were always a threat in the final third with Joel Porter leading the line well.
But they failed to make the most of their early possession and Northampton produced the first chance when Luke Guttridge saw his overhead kick fly just over from Danny Jackman's cross in the 12th minute.
Five minutes later Guttridge found Hawley in the box and he turned his marker to beat goalkeeper Arran Lee-Barrett from close range.
Kevin Kyle should have equalised in the 23rd minute when he got on the end of a low cross from James Brown but shot wide at the near post.
At the other end, Adebayo Akinfenwa should have extended Northampton's lead four minutes later when he was set free by Jackman's inch-perfect pass, but he failed to beat Lee-Barrett.
Pools twice went close just before the break with Kyle and Michael Nelson both heading straight at keeper Frank Fielding.
Hartlepool were more of a threat in the second half, but again failed to make the most of their opportunities.
Porter twice went close shortly after the restart and Andy Monkhouse missed their best chance in the 55th minute when he mis-kicked after being set up by Richie Humphreys.
Hawley almost doubled Northampton's advantage in the 66th minute after again turning well in the box, but this time Lee-Barrett was equal to the effort.
Kyle missed another chance to earn a point in the 88th minute as he hurriedly shot wide of the target from a good position.