The school regularly ranks within the top ten in New South Wales in terms of academic achievement, ranking 4th in the state in 2011 and 5th in the state in the 2017 Higher School Certificate (HSC),[5] and has produced numerous notable alumni – "Old Boys".

[8] The first day of instruction – for 46 boys – was on 1 October 1883 and was located in a building on Castlereagh Street, designed by Francis Greenway and constructed by convicts.

[12] In 1928, the school moved to its current location at Moore Park, on the fringe of inner-city Sydney.

The Sydney High School Old Boys' Union lapsed from 1895 to 1901 due to lack of enrolments.

[16] Once admitted and matriculated, students are further grouped according to their abilities,[18] as estimated by their scores in relevant fields in the Selective High School Placement Test.

The current Moore Park site hosts the Great Hall, other school buildings, tennis courts, a gymnasium, the Junior Quadrangle, and the Flat, a common low-lying area of land between Sydney Boys and Sydney Girls' High Schools.

Accordingly, and unusually for a state school, the school possess rowing facilities at the Outterside Centre at Abbotsford, which includes a dormitory, boat sheds, and three pontoons; playing fields at Centennial Park, with the Fairland Pavilion and the McKay Oval, a fenced cricket ground; and, facilities at the ANZAC Rifle Range, which are managed by the Sydney High School Rifle Club.

[38] In 2002, "[Sydney Boys High School] wanted a more sophisticated admissions process, and more freedom to choose its own students.

[41] Connolly stated that "any racial undertones to earlier campaigns were a thing of the past" and that "the benefit for the school this time is about tying it to its local community".

[43] As of the 2012 edition of the New South Wales Department of Education and Communities statistics, more than 80% of the students enrolled at Sydney Boys High School have a language background other than English;[44] however, this is not to suggest that these students and their parents or guardians are all recent immigrants or not proficient in English or, broadly, that the school is not necessarily lacking in diversity.

This drew allegations of Sydney Boys High School of being unmeritocratic in its selection process.

Brothers, sons, and grandsons of students or Old Boys have been allowed to enrol, though they may not have met the rigorous selection criteria.

The ability to obtain an education which is pitched at a level appropriate to the capacities of particular students, is the basis for the equality of opportunity, to which I have referred.

Scott Morrison, Prime Minister of Australia (2018–2022), is an alumnus of Sydney Boys High School.