The attack occurred when two keepers went inside to clean the tiger's cage at the Zion Wildlife Gardens in the city of Whangarei, about 200km north of Auckland.
The NZ Press Association reported the tiger grabbed one of the keepers and would not let go despite the efforts of other staff.
The attack was said to have been witnessed by a group of tourists.
The wildlife park was closed and the tiger was killed.
Police, agriculture and health and safety officials are investigating the attack.
A white tiger at the same park was reported to have been involved in an attack on another keeper earlier this year. The keeper had to have knee surgery as a result.
The zoo houses 42 rare lions and tigers.
