The school began when organizers of Saint Gabriel’s church opened an educational institution to provide better opportunities for students whom dropped school as the cause of the second world war in April 1946. The number of students at that time was only a mere 69 students and was located along Pudu Road English School. In December 1946, the number of students increased to 167 students. Reverend En Hua Yeh was the first principal.
In 1951 a land of no more than five acres was leased from the government to build the school. Prior to the main building that was completed,the enrolment of students grew up to 9 classes. The main building was seen cornerstone by His Highness the Sultan of Selangor, Sri Hishamuddin Alam Shah and Elah by Sir Gerald Templer was inaugurated on 10th January 1954
Up to 1957, secondary schools and primary schools were under the same administration. After the establishment of local authorities then there was separation between the secondary and primary schools.
In 1959, six classrooms (two workshops, two laboratories and two classrooms) were linked to the main building. At this time the school building was used by three schools (high schools, primary and private)
The number of students increased to 810 students in 1973 with a total of 31 teachers and staff of nine. From year to year, increasing the number of staf and students continue to grow.
In 1980 there were 1077 students start from level one to level 5. Given the rapid increase in students, secondary school St Gabriel provide a new system of division of students into the morning session (Grade 3 to 5) and the afternoon session (Transition, tingakatan 1 and 2)
