Wesley College, in Paerata at the northern end of Pukekohe, will close at the end of the school year.
"Student safety and wellbeing are our highest priority," Trust Board chair Jan Tasker said.
"We acknowledge that our hostel provision has not yet met the consistent standard we expect."
Wesley College is a Year 9 to 13 school founded in 1844 in Grafton.
The school is well known for producing All Blacks, notably Jonah Lomu.
A statutory manager was appointed to the board in 2023, with the notice removed earlier this year.
In a statement, the board said it accepted there needed to be structural change.
The hostels will only open again when the board can guarantee safety and student wellbeing, it said.
There will be a full review of the school's hostel culture, staffing and student care.
In another statement on the school's website, Tasker said the closures were not an easy decision.
"We are deliberately timing the closure for the end of term 4. This ensures that your children can complete NCEA and other examinations without disruption."
Tasker said there will be several actions during the closure:
• Undertake a full review of hostel culture, staffing, and student care.
• Invest in upgrading facilities and security.
• Strengthen safeguarding and supervision systems.•
• Work with the Methodist Church to ensure hostel provision fully reflects Wesleyan values of faith, service, respect and responsibility.
Staff at the hostels were being consulted with about their jobs.
The board said while progress has been made in improving the likes of safeguarding and culture, deeper change was needed.
The decision was about taking ownership and was a decisive step that would allow a reset once and for all, it said.
