Student Boards
There are seven major boards in the school, namely the Prefectorial Board, Board of Student Librarians, Editorial Board, IT Brigade, the Sportsmen's Board, SPBT Prefects Board and the Board of Student Cooperation.
Prefects
The Prefectorial Board was founded in 1931. The head of prefects in MBSSKL are known as School Captains (Kapten Sekolah) and not Head Prefects (Ketua Pengawas). In the event that a former School Captain should return to study in the school for the Lower and Upper Six form, he would immediately assume the post of Honorary School Captain and be part of the Executive Committee until the incumbent Executive Committee retires. Former Senior Prefects returning to study in the school for the Lower and Upper Six form are considered assets to the Board and are immediately reinstated. In any one academic year, a Vice Captain 2 may be elected in the Annual General Meeting if the position is deemed necessary. However, the position is reserved for a Form 6 Senior Prefect only.
Interviews for appointments as prefects are extended only to selected students after exhaustive vetting. Appointments to students of the Lower Sixth Form are reserved for girls. The interviewing panel consist of the members of the Executive Committee, although PROTEM EXCOs may take up this responsibility if the interviews fall after 31 July. Successful interviewees would undergo a period of probation where the duration is determined by the Executive Committee of the Board and the Advisor(s).
Inauguration of the in-coming elected Executive Committee and the installation of new Senior Prefects are held annually in a ceremony on Prefects' Day. Upon installation, the new Senior Prefects will wear a Prefect's Badge, which is the standard school crest with a blue banner beneath bearing the word "Prefect" in white lettering. A Prefect's name tag is yellow with navy blue lettering, and is worn immediately below the Prefect's Badge. The Executive Committee members of the Prefectorial Board are the only students in the school warranted to wear special school badges that bear their respective portfolio titles in white lettering on a blue banner beneath the school crest (e.g. Secretary), unlike the Executive Committee members of other boards where a separate tag is worn beneath their Board badges (i.e. The Librarian Chairman wears a tag stating his position - "Chairman of Centenary Library" below his Librarian's Badge and above his white name tag.).
Aside from maintaining student discipline, the Prefects are organisers of the annual Teachers' Day and are given near-total autonomy for all the activities in the event.
Librarians
The Board of Student Librarians proper was founded in 1962 although students who were voluntary helpers were formally given the title "Student Librarians" in 1957. In 1962, the current uniform of the librarians was designed by former teacher advisor Mrs. Sally Ti. The Librarians wear a Librarian's Badge, which is the standard school crest with a yellow banner beneath bearing the word "Librarian" . A Librarian's name tag is white with dark blue lettering, and is worn immediately below the Librarian's Badge. The Executive Committee members of the Board of Student Librarians retains their Board Badge and wears a separate tag bearing their respective portfolio titles.
Sportsmen
The Sportsmen's Club (Now Sportsmen's Board) was founded in the early 1970s. Membership to this board is extremely exclusive to those who excel in sports and character. Annually, less than 5 students are awarded membership to the Sportsmen's Board. The Sportsmen wear a Sportman's Badge, which is a silver pentadecagon with 120 decorative straight lines (8 lines between each vertices) projecting outwards engraved on the edge with the standard school crest in the centre encircled by a blue ring that bear the words "Lembaga Olahragawan Kuala Lumpur".
Information Technology Brigade
The IT Brigade was established in 2006 to develop the IT infrastructure in the school compound. Their duties include all computer-related issues of the school especially maintaining the Multimedia labs for the students' usage and computer repairs. The IT Brigadiers wear an IT Brigadier's Badge, which is the standard school crest with a black banner beneath bearing the word "IT Brigade". An IT Brigadier's name tag is silver with black lettering, finished with a clear protective layer, and is worn immediately below the IT Brigadier's Badge. The Executive Committee members of the IT Brigade retains their Board Badge and wears a separate tag bearing their respective portfolio titles.
SPBT Prefects (BOSS)
The Board of Student SPBT Prefects was established in 2012 to coordinate the loaning, returning and preservation of textbooks under the textbook loaning programme introduced by the Malaysian Ministry of Education. Apart from the annual loaning and returning of textbooks at the end of every academic year, they are responsible for making sure the textbooks are treated with care and respect throughout the loan period. The BOSS Prefects are trained to wrap books neatly (i.e. wrapping the covers tightly with minimal excess plastic wrapping) and cataloguing textbooks. The BOSS Prefects wear a BOSS Prefect's Badge, which is the standard school crest with a red banner beneath bearing the word "BOSS".
Editorial
The Editorial Board was established in 1906. Members of this Board do not wear special uniforms and may consist of students of any age. Membership from students in existing Boards are allowed as long as their prior responsibilities do not impede the progress of the magazine production. The Excelsior's Editor-in-Chief is assisted by his sub-editors and six other departments, namely Highlights, Organisation, Miscellaneous, Graphics, Photography, and Profiles. Every member is selected based on their strengths (e.g. writing, photography, etc.) and ability to work in a team. The teacher advisor and the team are given privileged access to all events related to the school so as to be able to capture important moments in photos and words for the Excelsior. The Board's duties regardless of whichever department is labour-intensive and requires precision in their works to be able to meet tight deadlines with external printers, photographers and binders.