The founder of the school was Rev. Alexander James Campbell. In April 1861 he formed a committee which resolved to establish a school under the auspices of the Presbyterian Church of Victoria. The Geelong College was formally established on Monday 8 July, 1861 at Knowle House in Skene Street Newtown with an enrolment of 40 pupils. The school aimed to ‘impart a first class education so as to prepare its pupils for entering the University and for following mercantile pursuits.’

The first Principal was Dr George Morrison, MA, a graduate of the University of Aberdeen and a man of outstanding scholastic and business ability. After three years, the committee assigned the College to the ownership of Dr Morrison. In 1871 the school moved into its new, purpose built building on an initial six-acre site on Newtown Hill – now the Senior School campus.

Dr Morrison was succeeded 1898 by his son, Mr Norman Morrison, who remained Headmaster until his accidental death in 1909. In 1908, after 44 years as a privately owned school, the College was transferred back to the Presbyterian Church to be governed by a Council set up by the Church. Also in 1908, the College became a member of the Associated Public Schools of Victoria.

In 1946, The College Council acquired a magnificent thirty-five acre property two kilometres west of the Newtown campus. The new Preparatory School was built there and opened in 1960. In 1974, the College became co-educational. In 1977, the greater part of the Presbyterian Church united with the Congregational Union and the Methodist Church to form the Uniting Church in Australia and, along with six other schools, the College became associated with the Uniting Church. At present, the Geelong College has an enrolment of approximately 1190 primary and secondary students.