St Mary's School is a private English medium, Anglican and boarding school for girls situated in the suburb of Waverley in Johannesburg in the Gauteng province of South Africa, it is one of the top and most academic schools in Gauteng.

John T. Darragh, who also founded its brother school St John's College, Johannesburg in Houghton ten years later in 1898.

[citation needed] St Mary's School writes the Independent Examinations Board exams.

St Mary's consists of four houses, each with a different colour, which compete in inter-house events such as hockey, tennis, swimming, athletics, squash, music, debating and theatre.

The houses are named after bishops of Johannesburg; Geoffrey Clayton 1934-1949 and Arthur Karney 1922–1933; bishop of Pretoria, Michael Furse 1909–1920 and archbishop of Cape Town, Francis Phelps 1931–1938.