Holly Wigg, of Wanaka, won two silver medals and Aja Tate-Bell, of Alexandra, won a bronze.
The competition was held in New Delhi last week.
Holly's mother, Caroline Wigg, said the New Zealand team was made up of about 30 athletes.
She said competition day was tough for Holly, who was entered in two categories held on the same day - Kata, which is set moves against another competitor, and Kumite, which is fighting.
Adjusting to the 41degC heat was also challenging and Holly was helped by Wanaka triathlete Dr Andrew McLeod to prepare.
''Having such good people in Wanaka ... and that great support network around her made a huge difference.''
Holly, who is a black belt, had been doing karate since she was 5 years old.
