After creating a number of first-half chances, the Terriers had to defend for long periods after the break as the lowly Bulls looked to snatch all three points.
Huddersfield goalkeeper Alex Smithies made two great saves from Lionel Ainsworth and Steve Guinan to keep his side in the match.
And, against the run of play, centre-back Nathan Clarke struck the ball home in the 70th minute when Bulls full-back Richard Rose only half cleared a shot from Danny Cadamarteri.
The home side wrapped up victory six minutes later when substitute Phil Jevons and Gary Roberts worked a neat one-two on the edge of the area and Roberts fired home his seventh goal of the season.
Lionel Ainsworth almost gave Hereford a lifeline but Smithies made another fantastic save.