Queens Park Rangers made it five wins in their last seven matches with a 5-1 victory over bottom-placed Rotherham United.
Luongo timed his run to perfection before meeting Yeni Atito N'Gbakoto's cross with a well placed headed to put Rangers 4-1 up.
The 24-year-old, who plays in a deeper midfield role at Loftus Road than he does with the Socceroos, was "buzzing" after the goal and was happy to poke fun now he had broken his duck.
QPR's turnaround has seen them move 10 points clear of relegation with just eight matches remaining.
Meanwhile, Scott McDonald has continued to show he can find the back of the net with regularity in Scotland, despite his struggles to do so in the past with the Socceroos.
McDonald missed an earlier chance to equalise after St. Johnstone's eighth-minute opener, but made no mistake in the 44th minute when he turned and swept the ball home after St. Johnstone failed to clear the ball.
Motherwell are in 10th position, and will likely be involved in the relegation play-offs come the end of the season.
Elsewhere, former Brisbane Roar forward Kwame Yeboah scored his eight goal for Borussia Mochengladbach's second team in the Regionaliga.
Jackson Irvine played 90 minutes in Burton Albion's 3-5 loss to Brentford, while also in the Championship Mile Jedinak completed 90 minutes as Aston Villa defeated Wigan 2-0 away.
Jedinak was Villa's most involved player, making 59 touches, 11 clearances and 35 passes as the former Premier League side move up to 12th position on 51 points.
Brad Smith and Trent Sainsbury were both unused substitutes for Bournemouth and Inter Milan respectively.