Catholic High School (CHS) is a government-aided autonomous Catholic boys' school in Bishan, Singapore, founded in 1935 by a French missionary, Reverend Father Edward Becheras. One of the Special Assistance Plan schools in Singapore, it has a primary section offering a six-year programme and a secondary section offering a four-year programme. Since 2013, it has partnered with Eunoia Junior College for a six-year Integrated Programme, which allows its secondary students to proceed to Eunoia for Years 5 and 6 and take the Singapore-Cambridge GCE Advanced Level examinations at the end of Year 6.

Catholic High School was founded in 1935 as Sino-English Catholic School (英华公教中学) by the Reverend Father Edward Becheras, a French missionary. Although it was a Catholic school, it accepted both Catholic and non-Catholic students, and was run along the lines of a Sino-English school. The school first started as an extension of the Church of Saints Peter and Paul. Fr Becheras envisaged the school as a bilingual institution from the start, emphasising instruction in both English and Chinese, a policy that continues today. In addition, Fr Becheras emphasised the teaching of science, uncommon at that time.

In 1936, Sino-English Catholic School moved into a purpose built school building at 222 Queen Street, beside the Church of St. Peter and Paul. Two years after the new school campus was completed, it reached its maximum capacity. Among notable features of the old school is the science room in the school, the first such feature in any Catholic school in Malaya.

In 1950, the Marist Brothers took over responsibility for the administration of Catholic High; a primary section was opened in 1951, with a new school building at 8 Queen Street. A boarding house for Catholic High students was also built. Under the supervision of the Marist Brothers, the school thrived along with Maris Stella High School, which was founded in 1958 to ease overwhelming applications for admission to Catholic High School.

In 1954, Catholic High School expelled all seventy students who were involved in the National Service riots for their absence from class, a move that shocked the nation. Catholic High School was the only institution that carried out expulsion as follow-up actions. The incident affirmed the school's zero tolerance of students' involvement in any political activities, and the school's stance of committed learning

Pre-university classes were offered in Catholic High School between 1952 and 1975, with a number of graduates attaining the President's Scholarship.

In 1956, Rev. Philippe Wu, the school’s second principal, relocated to Kuala Lumpur to establish Catholic High School, which was permanently moved to Petaling Jaya in 1958. The Marist Brothers subsequently expanded their mission by founding additional schools across Malaya and the North Borneo States (now Malaysia), including in Bentong (1957), Melaka (1958), Sibu (1960), and Tanjung Malim (1960). To this day, the schools in Singapore, Petaling Jaya, Melaka, and Sibu continue to share the same school anthem, with only the opening phrase adapted to reflect their respective locations, namely ‘公教中学 屹立星洲’ (Singapore), ‘公教中学 屹立雪州’ (Petaling Jaya), ‘公教中学 屹立甲州’ (Melaka), and ‘公教中学 屹立砂州’ (Sibu).

In 1974, the administration of the school was handed back to the Catholic diocese. Before the full nationwide adoption of the junior college system in 1975, Catholic High School was the only Chinese-medium high school in Singapore that offered both the Chinese-medium Senior High Certificate (华校高中文凭) and the English-medium Cambridge GCE Advanced Level examinations to all of its students.