The organisers of the Hidden Valley Festival say their "thoughts, respect and aroha" are with the family of the person who died at the event yesterday.
Emergency services were called to the festival after an attendee suffered a medical event about 7.30pm yesterday.
"Sadly, despite immediate medical assistance being provided to the person, they died."
In a statement posted to Instagram today, the organisers of Hidden Valley said they were deeply saddened.
"As a live music festival that prides itself on providing a safe and enjoyable experience for all, we are devastated by this tragic event," they said.
"Our thoughts, respect and aroha remains with the family of the deceased at this time.
"The safety and wellbeing of our attendees, artists, staff, security and support team remains our number one priority."
They say Hidden Valley will continue to follow health and safety guidelines set by police and local authorities.
A police spokeswoman told the Herald they were investigating the death on behalf of the coroner.
Know Your Stuff deputy manager Dr Jez Weston today said the cause of death was yet to be made public and they did not want to speculate.
"The death at Hidden Valley Festival is a tragedy. We are very sorry that the friends and family of this person find themselves in this heartbreaking situation."
The dance and electronic music festival, held at the Matakana Country Park north of Auckland on December 27, is one of the first major festivals of summer.