The annual competition consists of a geography quiz, essay writing and an orienteering round of geographical sites.
It was during the latter event that Andrew said he gained the crucial points which put him ahead of second-place winner and fellow school pupil Nat Christensen.
Competitors had to draw a "point of view" map incorporating key features of the Wellington skyline from the top of the Wellington cable car.
"Everyone else did it really quickly. I just took my time and I ended up getting top marks in the category. I guess you could say it was a bit like the fable, the tortoise and the hare."
Andrew and Nat also had success in the team event when they joined forces with another John McGlashan pupil, Duncan Wilson.
They won the event 15 points clear of the other competitors.
The team was selected to compete in the national final after winning the Southern Region Maatangi Whenua Geography Competition earlier this year and their success in Wellington was a surprise, Nat said.
"We weren't really sure what was going to happen - we weren't told a lot about what was going to be in the competition.
"It was quite different from the regional competitions."
The three pupils are now waiting to hear if they will be selected to represent New Zealand in the International Geography Olympiad in Japan next year.