Smith (14) won the shot put and finished runner-up to talented Sara Cohen athlete Ricky White (18) in the 200m and long jump.
In the long jump White jumped 5.09m and Smith 4.42m.
White also won the 100m.
Smith, who lives on a dairy farm at Clifden, was the only competitor from his school.
He will also represent Tuatapere Community College at the New Zealand secondary schools championships in Timaru next month.
Smith was one of the 102 athletes - up from 80 last year - from 16 schools competing in cold conditions.
A feature of the championships was the participation from Southland schools, with 14 athletes coming from James Hargest High School in Invercargill.
Mark Cook (15) won gold ribbons in the 100m, softball throw and 50m walk, and Justin Shepherd (16) was first in the 100m and the shot put.
These efforts pleased teacher aide Donna Henderson, who accompanied the team to Dunedin.
"It was all about participation for us," she told the Otago Daily Times.
"They surprised themselves with what they achieved."
Kings sprinter Ben Richardson (15) typified the spirit of the day with a gutsy display of determination in the 100m wheelchair sprint.
Jan Aitken, the regional sports co-ordinator for the Special Olympics, said "all the athletes had smiles on their faces and competed to the best of their abilities".
Otago Secondary Schools Sports Association sports director Des Smith was pleased by the jump in numbers from last year.
"We had schools from all over Otago and Southland participating and the kids had a lot of fun," he said.
"Competing at the Caledonian Ground was special for them."
