Luongo, 24, played a delightful cross for Idrissa Sylla to slide home in the 75th minute, allowing QPR to secure all three points.
It is the second time Luongo has assisted this season in 10 Championship appearances.
QPR are now in ninth position, one point off the crucial sixth promotion-playoff position.
Jimmy Floyd Hasselbaink, QPR's manager, praised his side's performance, "In the first half we were the better team and should have scored."
"It's always difficult when you've played that well and are not in front at half-time, but we were persistent and did the same in the second half.
"We went for it. It was always going to be a battle in midfield and about winning the physical battle. Whoever won that could then create, and we did that particularly well.
"We deserved the three points. It's always important to win at home and obviously it was in the backs of our minds. We have been unfortunate in the last few games but we cannot look back. What's important is what is now in front of us."
Meanwhile, fellow Socceroo Jackson Irvine played 89 minutes for Burton Albion in their 2-0 loss to Ipswich Town.
Aaron Mooy and Bailey Wright are in action tomorrow morning (AEDT) when Huddersfield visit Preston.