They have agreed to enter facilitated mediation with the assistance of an agreed independent mediator and to suspend all strike notices.
Fenz has also agreed to withdraw the request for facilitated bargaining through the Employment Relations Authority.
This agreement remains in place until September 30 or unless otherwise agreed upon.
The negotiations for a collective agreement began in June last year.
NZPFU has been attempting to gain guaranteed mental health and wellbeing programmes that meet the needs of firefighters and ongoing access to psychological professionals.
The union has also previously stated that there is "a fire crisis" with Fenz failing to employ sufficient career firefighters and 111 emergency call centre dispatchers to meet minimum staffing.
Although they are employed to work 42 hours a week, the union has said firefighters are largely working 60-80 hours and some report working 100 hours.
The NZPFU represents professional career firefighters, 111 emergency call centre dispatchers, volunteer support officers, community risk reduction and resilience advisers, trainers and other specialist roles.