Finn faced stiff competition from under-14 (youth C) competitors from Australia and New Zealand.
But he was up to the challenge, finishing third for the speed climb and fifth in the difficulty climb.
Racing up walls eight times during the knock-out competition did not seem to take much of a toll on the youngster, who completed each 5m ascent in about 12 seconds, before beating the fourth-placed competitor by 0.5sec.
Josh Evans, of Auckland, was second, behind winner Zac Fisher, of Australia.
In the difficulty event, the eight finalists, including Fairbairn, Evans, Adam Steens, of Mt Maunganui and Matthew Sutherland, of Rotorua, all went through to the final round on the same score.
Just six points separated the first and fifth competitors when the competition was completed, with Fairbairn placed fourth of the Kiwi finalists.
Finn said having Basecamp reopened was "brilliant" as he would be able to do his training in Wanaka from now on.
"I have been here just about every day and I work here as well, doing basically anything that needs to be done," he said.
Finn's unpaid labour earns him a free season pass and meals.
Finn has now turned his focus to the Wanakafest 24-hour climbing competition to be held from 4pm on Saturday at Basecamp.
He aims to complete 50 ascents within 24 hours and is also in a team that will continuously climb a ladder in an attempt to match the height of Mt Everest (8850m).
Funds raised at the event will go towards new computers at Finn's school, Mt Aspiring College.
