The following lists events that happened during 1921 in South Africa.
Incumbents
Monarch: King George V. Governor-General and High Commissioner for Southern Africa: Prince Arthur of Connaught. Prime Minister: Jan Smuts. Chief Justice: James Rose Innes.
Events
May
3 – The second census of the Union of South Africa takes place. 24 – The Bulhoek Massacre takes place with an estimated 163 killed.
July
30 – The Communist Party of South Africa is established.
December
28 – White gold miners on the Witwatersrand go on strike in the Rand Rebellion.
Unknown date
Dagbreek men's residence opens at Stellenbosch University.
Births
30 May – Jamie Uys, actor and film director. (d. 1996) 21 July – Vusamazulu Credo Mutwa, Zulu sangoma and author (d. 2020)
Deaths
10 September – John Tengo Jabavu, editor of South Africa's first newspaper in Xhosa. (b. 1859)
Railways
Railway lines opened
1 November – Transvaal – Pretoria West to Roberts Heights, . 28 November – Natal – Booth Junction to Cato Ridge, .
Locomotives
Two new Cape gauge locomotive types enter service on the South African Railways (SAR): February – A single experimental 2-6-0+0-6-2 Garratt articulated steam locomotive, the first Cape gauge Garratt in South Africa. June – The first of seven Class GB 2-6-2+2-6-2 Garratt locomotives.