Jason Kennedy's goal separated the sides for the majority of the contest and two late strikes from Jean-Louis Akpa Akpro and Chris O'Grady added gloss to the finish.
Rochdale took a one-goal lead into the break courtesy of Kennedy's sixth-minute strike. He fired home from close range when Brian Barry-Murphy's free-kick was headed goalward by Craig Dawson.
Graham Carey and Scott Arfield saw shots fly wide as the Terriers looked for an equaliser.
Huddersfield started the second half well, Arfield seeing a shot blocked while Carey's cross-shot had Josh Lillis scrambling across his line.
Lee Peltier crashed a shot into the side netting, but the game was up for Town in the 87th minute when Akpa-Akpro lifted a shot past Smithies and within a minute O'Grady crashed his effort into the roof of the net.