The first principal was Dulcie Flinn, who was previously of the Presbyterian Ladies' College, Melbourne.

1992 saw the purchase of a 1.6-hectare (4.0-acre) block of land adjoining the school from a plant nursery.

1996 was another year of building, including the Pre-Prep campus and Tew Field, as well as the adjoining Pavilion.

This building incorporates four stories which include a library, many computer facilities, multimedia studio and numerous staff offices and front desk.

2006 saw the renaming of the Arts Centre to the Founders' Building, in honour of those who started the school.

In 2007 The Knox School celebrated its 25th anniversary, along with unofficially opening its new auditorium, and beginning renovations to part of the Senior School, with renovations to the science labs and the conversion of the Year 12 Common Room into a hospitality kitchen, where students study the elective subject Food Technology and also serves as a small café for the staff.

The four Houses used for sporting and arts competitions and carnivals are "Chisholm" (named after Caroline Chisholm), "Flinders" (Matthew Flinders), "Lawrence" (Marjorie Lawrence) and "Paterson" (Banjo Paterson).