"I'm overwhelmed, honestly - great" was Mr Madill's response after learning he had won the $4000 award, having earlier won the painting and 2-D section award, and a further $1000, with his graphite drawing Unmanned.
Three other awards, each of $1000, were won by former Green MP Metiria Stanton Turei, photography; Peter McLaren, printmaking; and Kylie Matheson, 3-D.
Mr Madill (38) had worked on his art over the past 10 years, and supported himself through part-time jobs.
He had entered many competitions in the past and been selected to participate, but had never before won a big award. He was grateful for the "exposure" and welcomed the encouragement.
"I just want to get back in the studio and continue," he said.
The awards are a two-yearly exhibition sponsored by The Cleveland Charitable Foundation.
Society president Doug Hart said 193 works had been selected for the latest exhibition, reflecting a deliberate move to offer a smaller show after 364 works had been displayed two years ago.
