Established on 26 April 1909,[2] by the Anglican Archbishop of Melbourne, Henry Lowther Clarke, the school currently caters for approximately 1,200 students.

The Archbishop purchased 'Gawsworth', a property which stretched between Outer and Middle Crescents, and named the school after Firbank, his birthplace in Westmorland, England.

Florence Emily Green had founded and run the New England Girls' School before she sold it.

[3] Under the leadership of Maud Cameron, Firbank's longest serving Headmistress, enrolments grew and further land was purchased, including the 'Pen-y-bryn' estate and 'Atherstone' in Sandringham.

Since its foundation, Firbank has maintained a strong connection with St Andrew's Anglican Church, Brighton where formal school services are held.