Mrs Gibbons said the results were achieved by "putting faces to the data" and zeroing in on students who needed help.
"We tracked the students really vigorously last year. We would then have meetings with staff, looking at programmes, and making sure there was good mentoring," she said.
The dedication to getting as many students across the NCEA Level 2 line - considered the most important benchmark for school leavers - was such that students would stay late, and attend holiday programmes.
"Some even came in after the year was over to try and pick up the last of their credits," Mrs Gibbons said.
While the school's rate of attainment at University Entrance level was lower, the principal said that was partly because of the changes to UE requirements.
The school's deputy head girl, Victoria Thompson, 17, was one of the high achievers at Level 2, getting her subjects endorsed with excellence.
"The year before, I got a merit endorsement. But I knew I could do better and all my teachers encouraged me - they said I had the ability - and it made me try harder."