McCullough (17) broke away with a 13sec lead after a tightly-fought bike ride before winning the men’s event in 53min 27 sec, 12sec ahead of Portuguese silver medallist Alexandre Monties.
Describing the race as "touch and go," the Saint Kentigern pupil said it was an amazing feeling to come away with the top title.
"I didn’t look back the whole run.
"I thought it was pretty touch and go heading into the run so yeah to look back on the finishing straight and know I couldn’t see them, it was very cool."
McCullough admitted he felt the nerves coming into the event, but his mentor, former New Zealand international triathlete Rick Wells, was right alongside him the whole way.
"It’s a highlight of my life to watch that, just great to see," Wells said.
• Dunedin swimmer Erika Fairweather had her first races at the Youth Olympics yesterday.
The 14-year-old finished fourth in heat 3 of the women’s 100m and was part of the New Zealand team which finished fourth in heat 3 of the mixed 4x100 freestyle relay.
