| Cabinet Name: | First Vorster Cabinet |
| Cabinet Number: | 3rd |
| Jurisdiction: | the Republic of South Africa (since the 1961 Constitution) |
| Flag: | Flag of South Africa (1928–1982).svg |
| Flag Border: | true |
| Incumbent: | 1966–1970 |
| State Head Title: | State President |
| Government Head Title: | Prime Minister |
| Government Head: | Johannes Vorster |
| Political Party: | National Party |
| Legislature Status: | Majority |
| Opposition Party: | United Party |
| Opposition Leader: | De Villiers Graaff |
| Election: | 1966 election |
| Previous: | Verwoerd II |
| Successor: | Vorster II |
Following the assassination of Prime Minister Dr. Hendrik Verwoerd in parliament on 6 September 1966, Adv. Johannes Vorster became the next Prime Minister of South Africa. He appointed members of the National Party to the following positions in his first Cabinet:
| Prime Minister | Johannes Vorster | 13 September 1966 | 22 April 1970 | |
| Minister of Agriculture | Jacobus Fouché D. C. H. Uys | 13 September 1966 10 April 1968 | 10 April 1968 22 April 1970 | |
| Minister of Bantu Administration, Bantu Education and Development | M. C. Botha | 13 September 1966 | 22 April 1970 | |
| Minister of Defense | Pieter Willem Botha | 13 September 1966 | 22 April 1970 | |
| Minister of Economic Development | Nicolaas Diederichs Jan Haak | 13 September 1966 1967 | 1967 22 April 1970 | |
| Minister of Education, Art and Science | Jan de Klerk | 29 April 1974 | August 1978 | |
| Minister of Finance | Eben Dönges Nicolaas Diederichs | 13 September 1966 24 February 1967 | 24 February 1967 22 April 1970 | |
| Minister of Foreign Affairs | Hilgard Muller | 13 September 1966 | 22 April 1970 | |
| Minister of Forestry | Frank Waring Fanie Botha | 13 September 1966 9 August 1968 | 9 August 1968 22 April 1970 | |
| Minister of Health | Albert Hertzog Carel de Wet | 13 September 1966 9 August 1968 | 9 August 1968 22 April 1970 | |
| Minister of Home Affairs | P. K. Le Roux Lourens Muller | 13 September 1966 1968 | 1968 22 April 1970 | |
| Minister of Immigration | Alfred Trollip Connie Mulder | 13 September 1966 1968 | 1968 22 April 1970 | |
| Minister of Indian Affairs | Alfred Trollip Frank Waring | 13 September 1966 9 August 1968 | 9 August 1968 22 April 1970 | |
| Minister of Information | Jan de Klerk Connie Mulder | 13 September 1966 1967 | 1968 22 April 1970 | |
| Minister of Justice and Prisons | Johannes Vorster Petrus Cornelius Pelser | 13 September 1966 | 22 April 1970 | |
| Minister of Labour | Marais Viljoen | 13 September 1966 | 22 April 1970 | |
| Minister of Land and Land Administration | D. C. H. Uys | 13 September 1966 | 22 April 1970 | |
| Minister of Mining | Jan Haak Carel de Wet | 13 September 1966 9 August 1968 | 9 August 1968 22 April 1970 | |
| Minister of Police | Johannes Vorster | 13 September 1966 | 22 April 1970 | |
| Minister of Posts, Telegraphs and Telecommunication | Albert Hertzog Matthys van Rensburg | 13 September 1966 9 August 1968 | 9 August 1968 22 April 1970 | |
| Minister of Public Works and Community Development | W. A. Maree Blaar Coetzee | 13 September 1966 9 August 1968 | 9 August 1968 22 April 1970 | |
| Minister of Social Affairs and Pensions | W. A. Maree Connie Mulder | 13 September 1966 9 August 1968 | 9 August 1968 22 April 1970 | |
| Minister of Sport | Frank Waring | 13 September 1966 | 22 April 1970 | |
| Minister of Tourism | Frank Waring | 13 September 1966 | 22 April 1970 | |
| Minister of Transport | Ben Schoeman | 13 September 1966 | 22 April 1970 | |
| Minister of Water Affairs | Jacobus Fouché D. C. H. Uys Fanie Botha | 13 September 1966 9 August 1968 | 9 August 1968 22 April 1970 |