St Gabriel's School opened its doors on 3 June 1953 (costing $175,000 with a government contribution of $71,000) and stood at the junction of Hillside Drive and Upper Serangoon Road. Under the supervision of Rev Bro Louis Gonzaga (Founder) and seven pioneer teachers, the school accepted 212 pupils for its first intake, consisting of only five classes: two of Primary 1, one each of Primary 2, Standard 1 and Standard 2. The school was officially declared open on 13 December that year by Michel Olcomendy, Bishop of the Diocese of Singapore and Malacca. In 1954, Brother Elzear became the school's first full-time Director (Principal).