Boyd, on loan from Peterborough with a view to a permanent summer deal, rifled home his fourth goal in six games for the Tigers within 60 seconds of the second half, four days after making his Scotland debut against Serbia.
The 27-year-old's emphatic finish was a rare moment of class in a game bereft of clear-cut chances, but the win lift Steve Bruce's side four points clear of third-placed Watford.
Huddersfield, left looking over their shoulders at the other end of the table, were chasing back-to-back wins for the first time since October, but have slipped to within two points of the relegation zone and face a nervous run-in.
Hull striker Jay Simpson, playing alongside Boyd up front for the first time, fired an early volley straight at Huddersfield goalkeeper Alex Smithies.
The hosts responded soon after as Neil Danns sent a 20-yard shot fizzing inches wide, but neither side mustered a chance worthy of note for the next half an hour.
Hull midfielder Robert Koren's terrific cross from the left shortly before half-time had home defender Anthony Gerrard scrambling to hack the ball clear from under the crossbar, but that was the closest either side came to breaking the deadlock in the first half.
But Hull came bursting out of the blocks after the restart with Boyd's blockbuster giving them a 46th-minute lead.
Simpson threaded a fine diagonal pass into Boyd's path and although under pressure from covering Huddersfield defender Peter Clarke, the Scotland international lashed a rising shot into Smithies' top right-hand corner from the edge of the penalty area without breaking stride.
Huddersfield gathered themselves though and Danns' goalbound header from Jack Hunt's cross was well held by Hull goalkeeper David Stockdale.
There was plenty of huff and puff from the home side, but the final pass eluded them and in contrast, when Hull broke forward they looked a more well-oiled machine.
Boyd fired a left-footed effort straight at a grateful Smithies from David Meyler's cutback as the visitors senses a second goal would kill the contest.
Terriers manager Mark Robins sent on Danny Ward for midfielder Oliver Norwood and Clayton was replaced soon after by Sean Scannell.
Liam Rosenior and Corry Evans added fresh legs for Hull in place of Alex Bruce and Ahmed Elmohamady.
Hull keeper Stockdale deftly thwarted skipper Clarke's attempted cutback as Huddersfield tried to lift themselves for a late rally.
But Ward's 87th-minute free-kick summed up the home side's evening as it sailed harmlessly over the crossbar from a promising position on the edge of the area.
And in a frantic finish Hull defender Jack Hobbs threw himself in front of Danns after Stockdale had lost the ball to block the Huddersfield midfielder's shot.