Rex Morgan founded the Pittwater House Preparatory School for boys in 1961. Starting out with just six little boys, student numbers grew quickly and by 1964 land in Collaroy was purchased and a new Prep School building was opened for boys from 4 years of age to Year 6. By 1968 the new Grammar School was operational and Mr Morgan transferred ownership of the School to a non-profit company which owns and administers the School to this day. Parental demand for the educational approach offered to boys at Pittwater House led to the opening of the Girls College in 1975 so secondary school girls could share the campus with the Grammar School. The Junior Girls College followed, opening in 1977.
Through the early 1980s and 90s the number of school buildings at Collaroy grew to include a 15-room block and the Great Hall, the playing field, an Olympic short course swimming pool and tennis courts. Over the years, the school has continued to grow and evolve with the ongoing support of the Parents Association, Alumni and Government funding. Within recent years, some of the notable work by the parents has included the Mia Waters Memorial Terrace. The Parents Association also provided funding for the relocation and the initial refurbishment of the School Library and Media Centre. In 2009 the School received Australian Government Stimulus $1.7 million grant for the construction of the Pittwater House state of art indoor sporting stadium which was completed in September 2011. Further funding for the fitting out of the stadium was provided by parents and the School.
In 2003 Mr Richard Morgan succeeded his father as Principal of Pittwater House. Having already served the School as Vice Principal for the previous 15 years, Mr Richard Morgan was well placed to continue leading the School in the traditions established by the Founder.
Dr Nancy Hillier was appointed to succeed Mr Richard Morgan as Principal in October 2010. Since her appointment, Dr Hillier has reaffirmed the School's focus on providing for a balanced education that provides opportunities for students to develop their talents and skills in the academic and co-curricular areas. Dr Hillier is particularly interested in enhancing the student leadership experience and creating opportunities for personal growth through practical learning and in promoting a culture of professional development for teachers.