Built at a cost of $6.8 million and completed late last year, three of the classrooms will replace ageing rooms while seven will accommodate the growing school roll, from 1108 in 2010 to 1400 last year.
Whangarei Mayor Sheryl Mai officially opened the new classroom block on Thursday, situated at the corner of Manse St and Lupton Ave, in the presence of teachers, students and members of the school's board of trustees.
The new block called Manawa Ora (New Beginning) has five rooms upstairs and five downstairs.
Ms Mai, school principal Anne Cooper, headgirl Liv Crum and 2016 headgirl Justice Hetaraka spoke at the event before the plaque was unveiled.
The principal said staff and students loved the impressive building and its futuristic design.
Ms Hetaraka, who is presently studying law, said she was unable to see the construction of the new block during her time as a student but was glad it has finally been completed.
"The school had been a huge part of my life and that had a lot to do with the staff and people that work here. I am excited the present students will get to experience the warm and comfortable environment of the new classrooms."