1966
 

Our school was founded in 1966 by Fr. Howard D. Trube, an Catholic Foreign Mission Society of America(Maryknoll Fathers and Brothers), under the name of Maryknoll Practical Secondary School. Initially, it only offered courses for Form 1 to Form 3, with classes divided by gender—boys studying engineering and girls studying business—under the leadership of Father Trube.

At that time, the area around the school was still underdeveloped, and many residents nearby were from impoverished backgrounds, with limited access to education. The purpose of establishing this school was to provide educational services to underprivileged students, ensuring they had equal opportunities for education. To enable students to receive a complete secondary education, Father Trube established the Maryknoll College (Senior Form) the following year, offering Form 4 and Form 5 courses.

1978
 

In 1978, the school was renamed as Maryknoll Technical Secondary School and began offering a full-time five-year secondary curriculum.

In 1995, the school conducted its first Advanced Level Examination.

1997

In October 1997, the school was officially renamed Maryknoll Secondary School. It evolved from its original focus on business and commerce subjects to become a seven-year grammar school with balanced development across the arts, sciences, engineering, and business. At this time, the school also transitioned to a co-educational system.

2005

In September 2005, the new wing of the school was completed, providing students with additional specialized rooms to meet various teaching needs, allowing for a more comprehensive development in all areas.

In October 2015, the school successfully received approval for a new campus.

2022
 

On June 13, 2022, a handover ceremony was held in the hall of the new campus, after which the school immediately commenced facility optimization works.

On September 1, 2022, the new school year began smoothly at the new campus, with teachers and students witnessing a new chapter for Maryknoll Secondary School..

2023
 

On August 31, 2023, our Choi Ha Road campus was officially handed back to the government.

On September 1, 2023, Maryknoll Secondary School was officially returned to the direct management of the Catholic Diocese of Hong Kong. Our school will uphold its excellent teaching traditions and combine them with outstanding facilities to continue providing quality education under the leadership of the diocese, nurturing students to become caring and diligent .