Ms Kulasingham encouraged other women to have the confidence to get into jazz. "Just give it a go and have fun," she said.
The band consisted of Tina Jeong, 16, on trombone, Bianca Goyena, 16, on guitar, Kayla Ross, 15, on drums, Darrel Nitschke, 16, on vocals, and Anna Scherrer, 17, on tenor saxophone.
Director of the National Youth Jazz Competition Liam Ryan said bands had come from all over New Zealand, from Kerikeri to Christchurch.
"It's truly a national jazz fest," he said.
"What we are seeing is a deepening of the skill level and understanding of jazz by school music students.
"If jazz is about breaking down barriers then the National Youth Jazz Competition epitomises that."
Bianca Goyena from the group won the Mayers Music Centre Trophy for the most outstanding guitarist.
Tauranga Boys' College Big Band and the combo Plum Jam from Tauranga Boys' College picked up a Gold Award, and Tauranga Girls' College Big Band and the Sextet Pistols won a Silver Award at the competition.