The school is situated on a large area of land in the eastern suburb of Marryatville, part of the City of Norwood Payneham and St Peters.

[citation needed] The Junior Technical School continued to expand at the Osmond Terrace site, and in 1944 the Education Department bought 20 acres on Kensington Road at Marryatville.

In 1964 the school enrolment was 695 boys, 784 students attending night classes, and the Astronomical Observatory opened.

The first principal was Glen McArthur, who served in the position till 1991, by which time the school had a well-established reputation and enrolment.

The Marryatville High School big bands have also won music competitions around the country, notably at Generations In Jazz several times over recent years.

For the official opening of the school's theatre in 2005, a production by drama students was presented to guests including then South Australian Premier Mike Rann and state member for Norwood Vini Ciccarello.

When talking to the cast and crew after the opening show, Mr Rann exclaimed, "I've never seen anything this good, at either a High School, University or TAFE".

[11] Eden Park, a grand two-storey Victorian house, is now used as the high school's Year 12 campus; the timber stables have been converted into a music centre.

H Block is predominantly used for the sciences, having lab classrooms which include Bunsen burner gas valves, sinks, and other scientific equipment.