The West Yorkshire side took control with first-half goals from Izzy Brown and Nahki Wells.
Substitute Luke Freeman netted on the hour mark with his first QPR goal, but the visitors held on for a fourth consecutive league win and their first ever at Loftus Road.
To add to Luongo's woes he picked up a late yellow card as his side slumped to defeat.
On-loan Chelsea youngster Brown, who also scored against QPR while on loan at Rotherham United earlier in the season, struck on 26 minutes.
A slick Terriers move culminated in Wells crossing low from the left for Brown to score from close range - the 20-year-old midfielder's fourth goal in six starts since joining Huddersfield.
And the impressive Wells doubled the lead after another fine move 10 minutes later, rifling a right-footed shot into the far corner from right-hand side of the penalty area.
Freeman, recently signed from Bristol City, hauled QPR back into the game eight minutes after coming off the bench.
Huddersfield were unable to clear Kazenga LuaLua's cross from the left and when the ball dropped to Freeman 20 yards out, he fired home.
QPR were very much second best up to that point, although Conor Washington had almost given them an early lead.
After some neat QPR link-up play, Grant Hall slipped the ball through to Washington, whose shot was tipped on to the post by keeper Danny Ward.
Recent signing Matt Smith, making his full debut for QPR, sent a volley well over the bar and headed straight at Ward from Ryan Manning's left-wing corner during a decent first-half spell for the home side.
Manning volleyed wide shortly before excellent passing and movement led to the opening goal.
The second was even better, with Huddersfield calmly moving the ball from one end of the pitch to the other - to cheers from their travelling fans - before Wells applied the emphatic finish.
With his team showing no sign of improvement in the early stages of the second half, QPR boss Ian Holloway made a double substitution, sending on Freeman and LuaLua.
The change quickly paid off, with on-loan Brighton & Hove Albion winger LuaLua creating an opening and Freeman taking full advantage.
QPR would have followed that up with an equaliser but for a brilliant save from Ward, who denied Smith at point-blank range after the target man had been set up by Washington.
And Holloway's side appealed in vain for an 89th-minute penalty after Smith's header appeared to strike Michael Hefele's hand. Seven minutes of injury-time increased the tension for Huddersfield fans, but David Wagner's team stood firm.