The Austrian demonstrated nerves of steel producing the only clean run down the 23 gate course to win in 98.48.
Leitner surprised even himself winning the gold medal having earlier finished fourth in the semifinal.
“I never thought (winning gold) was going to happen. I went out to do every run as fast as I can”, Leitner said.
“I was really excited going into the race. The first gate was good and the second was the best – I did it exactly as my coach said to.”
The win was a massive improvement for Leitner who finished 17th a year ago in Slovakia.
Four other paddlers produced quicker raw times than the Austrian but gate touches proved costly.
Slovenian Vid Kluder Marusic improved on his semifinal run by three seconds to take home the silver in 99.47.
Marusic took his time through the first six gates, but had to change his approach after a touch on gate eight.
“After that I knew I had to get two seconds back and take some risks and the risks paid off. I had to fight to the end”, Marusic said.
Reigning champion Jakub Grigar of Slovakia finished third 0.29 seconds behind Marusic.
Grigar, who celebrates his 17th birthday tomorrow was unable to repeat the form he demonstrated in the semifinal.
“I felt pretty nervous at the start and I wasn’t so good at the back end and made mistakes at on the upstream gates”, Grigar said.
Slovenian Niko Testen was the unlucky fourth placed paddler, missing a medal by 1.93 seconds.
Local Penrith kayaker Angus Thompson paddled beyond his years to finish 10th.
It was marked improvement on his 21st placing at Liptovsky Mikulas last year.
“It is progress – competing against the guys again and to get ahead of them. They smashed me last year”, Thompson said.
Official result below.
Junior K1M Final
1. Mario Leitner (AUT) – 98.48
2. Vid Kluder Marusic (SLO) – 99.47 (2)
3. Jakub Grigar (SVK) – 99.76 (2)
4. Niko Testen (SLO) – 101.69 (4)
5. Mathurin Madore (FRA) – 103.45 (6)
6. Richard Macus (SVK) – 108.02 (4)
7. Leo Bolg (GER) – 116.04 (4)
8. Callum Gilbert (NZL) – 126.88 (2)
9. Zachary Allin (GBR) – 158.00 (54)
10. Angus Thompson (AUS) – 160.08 (54)