| John Smith MacIvor | |
| Birth Date: | March 27, 1913 |
| Birth Place: | Glace Bay, Nova Scotia, Canada |
| Death Place: | Sydney River, Nova Scotia, Canada |
| Office1: | MLA for Cape Breton South |
| Term Start1: | 1945 |
| Term End1: | 1956 |
| Predecessor1: | Donald C. MacDonald |
| Successor1: | Donald C. MacNeil |
| Office2: | Speaker of the Nova Scotia House of Assembly |
| Term Start2: | 1954 |
| Term End2: | 1956 |
| Predecessor2: | W. S. Kennedy Jones |
| Successor2: | Gordon E. Romkey |
| Party: | Liberal |
| Occupation: | lawyer |
John Smith MacIvor (March 27, 1913 - June 12, 1957) was a lawyer and political figure in Nova Scotia, Canada. He represented Cape Breton South in the Nova Scotia House of Assembly from 1945 to 1956 as a Liberal member.
He was born in Glace Bay, Nova Scotia, the son of Malcolm MacIvor and Catherine Smith. He was educated at Acadia University and Dalhousie University. MacIvor practiced law in Sydney and served as provincial magistrate from 1942 to 1945. He was chosen as speaker for the provincial assembly in 1954.[1]