Together with his older brother, five older sisters, mother, and father, Uwe Balzat, the family played instrumental folk music in a family band around Auckland where they live.
Instruments included violins, flute, cello, guitar, keyboards and drums.
Viv Balzat, a piano teacher, home schooled her children with Matthias finishing his secondary education by the time he was 13.
She said Saturday's win would help further Mathias' career in Germany later this year when he hopes to be accepted for further study in Berlin.
"The win is the cream on top. It's a huge help for his future."
He is currently completing honours and will audition in June for places with Jens Peter Mainz or Wolfgang Schmidt in Berlin to undertake his masters.
Because it was the 50th anniversary of the competition, finalists were accompanied by the New Zealand Symphony Orchestra instead of the Christchurch Symphony Orchestra.
"For Matthias, just to get the opportunity to play with the NZSO was a big thrill."
Viv Balzat said she was very proud of her son, largely because of his dedication and determination.
"He's put a lot in. He's very dedicated to his craft and what he wants to do. At the same time he's quite chilled but he comes alive on stage."
The competition usually alternates annually between piano and instrumental. However, this year's 50th jubilee meant there was an instrumental and a piano final, with two finalists from each.
Siyu Sun from Christchurch took out the top spot for the piano final ahead of Delvan Lin from Auckland.
Balzat's achievement is the fifth consecutive win for Waikato cellists at the competition according to James Tennant of the University of Waikato's Conservatorium of Music.
Tennant said for Balzat and Hye In, who moved to New Zealand from South Korea in 2008, playing with the New Zealand Symphony Orchestra was the stuff of dreams.
"Being so young at 17 and playing with our nation's most prestigious musical institution was a dream come true for them," Tennant said.
"Both students are heading towards international careers as soloists, so this was a wonderful opportunity to get a real taste for what might become a regular experience for them."
Last August Balzat won the Wallace International Cello Competition while Hye In has also won prizes in New Zealand and Italy.