Northland Regional Council chairman Bill Shepherd and council member Paul Dimery officially presented the Green-Gold during a ceremony at the 550-pupil school in Whangarei on Thursday.
The regional council introduced the popular programme to Northland in 2004 and there are now more than 90 schools and kindergartens in the programme region-wide.
"Onerahi School is one of our Northland pioneers in the programme and has been with us from the start," Mr Shepherd said.
Mr Dimery said Enviroschools' recognition came in three bands, from the most-often awarded Bronze, through to Silver and the rarest Green-Gold.
Susan Karels, the council's Enviroschools regional co-ordinator, said among Onerahi School's key strengths was its strong connection with its local community.
Mrs Karels said while the new Green-Gold status belonged to the entire school community, principal Gerald Koberstein deserved special mention for the way he had consistently led the programme from the beginning.