Coach Karen Holder said it was a fabulous start to the season.
"The festival is a superb event, and a wonderful opportunity for player and team culture development," she said.
"The chance to mingle with top class international players, many of whom will be representing their countries in Rio, is just not something that comes along every day."
The win came off the back of a big year for the team.
They came second in last year's Furnware Cup, and were promoted to the national first division after taking out the Chica Gilmer Trophy in September.
Earlier last week, the school also triumphed with students winning first place in the regional round of the 2016 University of Otago Sheilah Winn Shakespeare Festival, sending them through to the National Festival in Wellington.
Iona's director of performing arts Lisa-Jane Easter said her students had shown "brave commitment to dealing with the challenges presented by one of Shakespeare's most difficult works".
The students had been challenged by making the performance gender neutral, performing the play in a modern context and choreographing a stage fight.
With more than 40 hours of rehearsals, they were said to have delivered a performance which was "convincing, highly-charged and dramatic".
