Wright sped down the rocky track in 3:02.51 to edge out world-ranked stars Brook Macdonald and Sam Blenkinsop by a second to claim the honours.
The young rider was blown away with his efforts which he hopes will spark interest in him as he plots his first international season.
"I am totally stoked. It was a good gnarly track and most of the big professional Kiwi riders were here," Wright said.
After the seeding runs he was placed second to Ed Masters.
"It gave me a little bit [of confidence] but I also knew I had to give it a bit to get to the guy who was in first, so I went hard and it worked out for me - I was really confident on the track and felt I could push it on a bit and it worked out.''
After the seeding was determined, everything hinged on the one run - just over three minutes of action.
"I was thinking go out and have fun and treat it like any other practice run. It got a bit squirrely in some places but all went pretty much to plan."
He had one close call when it could have all gone terribly wrong.
"I was coming over a rise and I jumped a bit far over and landed in some rocks and tussock - that was a bit sketchy. But you get one run and you either do it or you don't."
With two huge events coming up Wright is on the cusp of realising his dream of becoming a professional rider.
"I received a scholarship after the Giant 2W Gravity Enduro in Rotorua and that has allowed me to spend more time training, but also to look at going overseas this year."
He will line-up in the Oceania Championships in Australia two weeks and the Crankworx event in Rotorua, hoping to secure some valuable UCI points in both events to get inside the top 80 on the World Cup downhill circuit to aid his opportunities at the major events.
Altherm Downhill Championships - selected results:
Elite men: Keegan Wright (Descend Rotorua) 3:02.53, 1; Brook Macdonald (Hawkes Bay, GT Factory) 3:03.45, 2; Sam Blenkinsop (Gravity Canterbury, NORCO Factory Racing) 3:04.23, 3; Rupert Chapman (Gravity Canterbury, Pivot Factory Racing) 3:04.66, 4; Wyn Masters (Descend Rotorua, GT Factory Racing) 3.04.82, 5.
Under-17: Alex Barke (Queenstown) 3:20.79, 1; Finn Parsons (Descend Rotorua) 3:22.13, 2; Blake Ross (Pohutukawa Club Auckland) 3:23.55, 3.
Under 15: Guy Johnston (Wanaka) 3:29.70, 1; James Macdermid (Descend Rotorua) 3:33.71, 2; Riley Adlam (Queenstown) 3:39.51, 3.
Elite women: Alanna Columb (Queenstown) 3:44.38, 1; Agata Bulska (Gravity Canterbury) 4:05.75, 2; Amanda Monk (Whakatane) 4:16.99.
Under-19: Shania Rawson-Pickard (Descend Rotorua, MTB Performance Hub) 3:45.68, 1; Emma Bateup (Bike Methven) 4:32.74, 2.
Senior: Ashley Bond (Descend Rotorua) 5:19.23, 1.