Australian professional Adam Burdett led the way on a five-under 66 to claim his spot with Koh then in a playoff with Australian pros Dale Williamson and Chris Akers for the other two spots. All three birdied the 18th before Akers went out of bounds on the second playoff hole to present Koh and Williamson with their tickets to Queenstown.
Koh has endured a tough initiation in Australia and New Zealand since turning professional last year, although he will head to his third straight New Zealand Open after his debut as an amateur in 2015 and receiving a New Zealand Golf invite last year.
"I would have liked to have got their outright today but I was pleased with my final 11holes," said Koh. "When I found myself over par today I just kept a cool head and didn't think too much about it.
"I was fortunate to have had a local caddy today and he really helped me, so much so that he is coming to Queenstown to carry my bag this week."
Koh, who is a member at both Whitford Park and the new Windross Farm in south Auckland, said there is nothing he would like more than to make it into the weekend.
"I like playing in Queenstown and I am really looking forward to playing the weekend at Millbrook Resort which is a course I really like."
Top qualifiers at Cromwell today were Christchurch amateur McLean, a greenkeeper at the Harewood Golf Club, and Fiji professional Sam Lee, who both fired five-under par 67s.
Muriwai amateur Kevin Koong and Tauranga's Karl Knedler shared third place on four-under 68, with the North Harbour player winning through on the first playoff hole.
The 93rd ISPS Handa New Zealand Open is a NZ$1 million Tier One event on the PGA Tour of Australasia, in partnership with the Japan Golf Tour and Asian Tour, to be played in Queenstown at Millbrook Resort and The Hills from 9-12 March.