Assumption English School was founded in 1953 by Brother Vincent, a Gabrielite Brother as one of the three components of Boys' Town. It was then known as Boys’ Town English School.
, Assumption English School was established as a single session, full school with classes from Primary One to Secondary Four, the School presented its first batch of students for the School Certificate Examination.
In 1973, the Secondary section of CHIJ Bukit Timah merged with Boys’ Town English School and the school became a Co-educational Catholic mission School.
The School took on the name of Assumption English School in honour of our Lady, Mother Mary, the Patroness of the Brothers of St Gabriel
The school progressed rapidly and in 1989, the school authorities decided to upgrade the facilities to better meet the demands of education for the new millennium.
In December 1992, the Primary Section of the school closed and the students were absorbed by St. Anthony’s Primary School.
Building of the new school building started in 1993.
The $20 million new school building was officially opened on 16 August 1997 by the then President of Singapore, the late r Ong Teng Cheong.