David Wagner's side went into the match searching for the win that would all-but guarantee their top-flight survival, but strikes from Cenk Tosun and Idrissa Gueye condemned them to a 2-0 defeat in front of their own supporters.
The Blues went on the offensive right from kickoff and won a corner inside the first minute when Terence Kongolo put the ball behind under pressure from Croatian youngster Nikola Vlasic, but Wayne Rooney's resulting cross was easily cleared by the Terriers' defence.
Huddersfield claimed the first shot on target in the 17th minute as Steve Mounie cut inside the box from the left and let fly, his effort taking a deflection before ending up in the arms of Everton goalkeeper Jordan Pickford.
Everton did not manage an attempt at goal until just before the half-hour mark when a corner fell kindly to Rooney on the edge of the box and the former England international let fly, his effort bobbling harmlessly wide of the near post.
Huddersfield came close to an opener moments later when Alex Pritchard escaped his marker at the byline and played a cross into the centre of the box where Rajiv van La Parra was lurking, but the Dutchman blazed his shot over the bar.
The Blues took the lead against the run of play following a swift counter in the 39th minute, a move which ended with Theo Walcott picking out Tosun inside the box and the Turk placing a low shot into the bottom corner.
Sam Allardyce's side went straight on the offensive in the second period too as Walcott used his pace to carve out a chance for Vlasic, whose first-time shot was directed straight at Jonas Lossl in the Terriers' goal.
Everton almost put themselves out of sight just before the hour as Vlasic picked out the run of Seamus Coleman along the right channel and the Irishman cut inside the box, but Lossl raced off his line and made himself big to block the wing-back's shot.
The hosts almost gave themselves a lifeline in the 64th minute when Van La Parra found space on the flank and played a low pass to Pritchard inside the box, only to watch his teammate stumble as he let fly, scuffing his shot off target.
The Blues made the points safe in the 78th minute when good work from substitute Oumar Niasse picked out Leighton Baines's run on the edge of the box, allowing the wing-back to square a pass to Gueye, who rifled a powerful shot into the back of the net.
The Huddersfield heads dropped after the second goal went in and they failed to create anything noteworthy in response for the remainder of the match.
Defeat leaves them in 16th place in the table, now just three points above the dropzone with as many games left to play, while Everton stay eighth.
HUDDERSFIELD (4-2-3-1): Lossl; Hadergjonaj, Jorgensen, Schindler, Kongolo; Hogg (Malone 62'), Mooy; Quaner (Billing 59'), Pritchard, Van La Parra (Depoitre 75'); Mounie
EVERTON (4-2-3-1): Pickford; Coleman, Keane, Jagielka, Baines; Gueye, Schneiderlin; Rooney (Tom Davies 63'), Walcott, Vlasic (Funes Mori 75'); Tosun (Niasse 72')