The school's 29 competitors came away with 38 medals, claiming 21 golds, seven silvers and 10 bronzes to pip Auckland’s Daredevil school to the title by just one point.
The points were awarded as three for a gold, two for silver and one for bronze.
It was Oceanside’s second consecutive year finishing in top spot, after winning the No-Gi discipline last year.
This year’s competition included both Gi and No-Gi for the first time, each representing competing with or without the sport's traditional outfit.
Co-founder and coach Hayden Smith said the school’s growth in recent years has been impressive. After starting in 2019 with just four members, it now boasts more than 200.
“It's pretty amazing to see,” Smith said.
“We were one of the hardest hit during Covid with (jiu jitsu) obviously being a contact sport, which is the complete opposite to social distancing.
“To be the biggest school now in the South Island and probably in New Zealand it's pretty special considering where we've come from.”
The club, which is based at the South New Brighton surf club, finished with 73 wins and 47 losses at the national championships.
Cuan Jones, Leo Pavlenko, Hudson Bowater, Eli Watson, Enzo Mediavillo and Dylan Baxter each came away with two gold medals, competitors limited to two events they could enter.
Oceanside is the only school outside Auckland to win the national title, which Smith said showed the growth of the sport in Canterbury.
“We're looking at actually expanding our space and potentially extending the mat area, offering more classes and having more coaches because the growth is just insane.
“I volunteer and help out low decile schools in Christchurch, Haeata Community Campus and Te Aratai College and get kids in from these schools from very hard backgrounds where there's no way they would be able to pay a membership, and I offer them free training once a week.
“We've seen massive positive change in these kids coming in from such rough backgrounds.”
He said he was hoping to continue the growth in years to come.
“Our next goal is to try and get up to 300 members and expand our gym,” he said.
