| St Mary's School, Waverley | |
| Motto: | la|Candida Rectaque |
| Motto Translation: | Honest and upright |
| Type: | Private & Boarding |
| Religion: | Anglican |
| Sister School: | St John's College, Johannesburg |
| Locale: | Suburban |
| Grades: | 00012 |
| Gender: | Female |
| Head Name: | Headmistress |
| Head: | Deanne King |
| Head Name2: | Exam board |
| Head2: | IEB |
| Zipcode: | 2090 |
| Coordinates: | -26.1415°N 28.078°W |
| Students: | 1,057 girls |
| Lower Age: | 3 |
| Upper Age: | 18 |
| Schedule: | 07:30 - 14:15 |
| Language: | English |
| Colours: | Blue, red, white |
| Campus: | Urban Campus |
| Alumni: | Old Girls |
| Free Label: | School fees |
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.
Established in 1888, it is the oldest school in Johannesburg. It was founded by the Anglican clergyman the Rev. John T. Darragh, who also founded its brother school St John's College, Johannesburg in Houghton ten years later in 1898.
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.
Pupils in grade 0 are placed in houses in the first term and stay through grade 7.
The house system was introduced in 1934 and students wear their house badges on their blazers with pride. 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.