| Cabinet Name: | Second Smuts ministry |
| Cabinet Number: | 4th |
| Jurisdiction: | the Union of South Africa |
| Date Formed: | 5 September 1939 |
| Date Dissolved: | 1948 |
| Government Head: | Jan Smuts |
| State Head: | George VI |
| Political Party: | United Party Dominion Party Labour Party |
| Election: | 1943 |
| Opposition Party: | Purified National Party (1939–1940) Herenigde Nasionale Party (1940–1948) |
| Opposition Leader: | Daniel François Malan (1939–1940) J. B. M. Hertzog (1940) Daniel François Malan (1940–1948) |
| Previous: | J. B. M. Hertzog government |
| Successor: | Daniel François Malan government |
Jan Smuts became South African Prime Minister for the second time in 1939, following a split in the United Party. He appointed members of the United Party, Dominion Party and Labour Party to positions in his Cabinet.
The 1938 general election was won by the United Party, giving J. B. M. Hertzog a fourth consecutive term. In September 1939, the United Party was divided between supporters of Hertzog and those of his Justice Minister Jan Smuts. The split resulted from differences between supporters of neutrality in World War II and those who wanted South Africa to follow the United Kingdom and declare war against Nazi Germany. Finally, Hertzog was outvoted within the United Party and Parliament. He resigned his post as Prime Minister, allowing Jan Smuts to form a new government in coalition with the Dominion Party and Labour Party.
| Party key | United Party | |
|---|---|---|
| Dominion Party | ||
| Labour Party | ||
| Office | Name | Dates | |
|---|---|---|---|
| Prime Minister | Jan Smuts | 5 September 1939 – 7 July 1943 | |
| Minister of Defence | |||
| Minister of Foreign Affairs | |||
| Minister of Agriculture and Forestry | William Richard Collins | 5 September 1939 – 7 July 1943 | |
| Minister of Commerce and Industry | Richard Stuttaford | 5 September 1939 – 1941 | |
| Minister of Commerce and Industry | Sidney Frank Waterson | 1941 – 7 July 1943 | |
| Minister of Education | Jan Hendrik Hofmeyr | 5 September 1939 – 7 July 1943 | |
| Minister of Finance | |||
| Minister of the Interior | Harry Lawrence | 5 September 1939 – 7 July 1943 | |
| Minister of Public Health | |||
| Minister of Justice | Colin Fraser Steyn | 5 September 1939 – 7 July 1943 | |
| Minister of Labour | Walter Bayley Madeley | 5 September 1939 – 7 July 1943 | |
| Minister of Social Affairs | |||
| Minister of Lands | Andrew Meintjes Conroy | 5 September 1939 – 7 July 1943 | |
| Minister of Mines | Charles Stallard | 5 September 1939 – 7 July 1943 | |
| Minister of Native Affairs | Deneys Reitz | 5 September 1939 – 7 July 1943 | |
| Minister of Posts and Telegraphs | Charles Francis Clarkson | 5 September 1939 – 7 July 1943 | |
| Minister of Railways and Harbours | Frederick Claud Sturrock | 5 September 1939 – 7 July 1943 | |
| Minister without portfolio | Pieter Voltelyn Graham van der Byl | 5 September 1939 – 7 July 1943 | |