This week the school, with a roll of almost 900 students, completed an "amazing" ERO review.
Feilding High School has a current roll of 1430 students, a boarding house of 190 students and also owns a dairy farm and sheep and beef farm which they are currently using to develop innovative Agribusiness courses for students.
Board of Trustees Chairman David de Lange said: "We are of course sad to be losing Mr O'Grady but understand the unique challenge that Feilding High School will present to him and wish him well on the next part of his career."
Last October, Mr O'Grady received one of just five National Excellence in Leadership awards.
The Cognition Education Trust worked through more than 600 nominations from early childhood, primary, intermediate and secondary schools, in order to whittle down the country's top educators.
At the time, the modest principal did not take any credit, instead insisting that his win came down to the staff and students he was honoured to represent.
Current deputy principal Michael Leitch will assume the acting principal's role for term one in 2016, while the board conducts a recruitment and appointment process.