A year later the school's premises were moved to the opposite of Pioneer Methodist Church Sitiawan, which it still stands as of today.

One year after Malaya gained its independence from the British (1958), the primary and secondary schools were separated.

The first Form 6 science stream class started in 1973 with a total of 24 students, preparing for the Higher School Certificate (H.S.C) examinations.

In 2009, the ACS Secondary School Sitiawan had 986 boys and 805 girls, making a total of 1791 students, supported by 123 teachers.

As for the primary school in the same year, it had 624 boys and 491 girls, making a total of 1115 students, supported by 69 teachers.

Currently, ACS Sitiawan is one of the largest schools in terms of students enrolment, from standard one to form six and consistently achieving excellent academic results at UPSR, PT3, SPM and STPM levels while having strong extra curricular achievement in various fields, producing alumni with solid background in various industrial as well as academic fields.

As the most prestigious school in Manjung, ACS Sitiawan too offers Chinese, Tamil and German as an initiative to ensure students are able to master at least three languages, in line with the Malaysian Ministry of Education.

Throughout its history, the band has involved in various activities such as marching with formations, street parade as well as wind orchestral competition.

Each year, the Interact Clubs will conduct charities such as recycling old materials, car wash services and also hosting the largest carnival in the school, dubbed Interact Carnival, selling foods and drinks as well as games to be played.

This room was an initiative by the former principal Mr. Ding Kong Leong that served the school from 2013 until his retirement in 2017.

The band had once won the best drum major award in district level in the year 2006 where the competition was held in the school field.

The band had once collaborated with Bethel Wind Symphony Orchestra from the United States to perform a concert in 2011.

ACS Military band was involved in Royal Malaysian Navy Day parade in 2014, 2018 and 2019 respectively.

On 31 August 2020, ACS Military Band won a silver medal in the Online National Marching Parade Competition in conjunction with the country's 63rd anniversary of independence.

Students of the ACS Sitiawan are also active in various activities, such as joining the Langkawi International Regatta, national level sailing competition, football, badminton, taekwondo, chess, track and field, English debate, public speaking in English, cross country and silat.