| Honorific-Prefix: | The Honourable |
| Josiah Burr Plumb | |
| Office1: | Speaker of the Senate of Canada |
| Term Start1: | 4 April 1887 |
| Term End1: | 12 March 1888 |
| Office2: | Senator for Ontario |
| Term Start2: | 8 February 1883 |
| Term End2: | 12 March 1888 |
| Nominator2: | John A. Macdonald |
| Office3: | MP for Niagara |
| Predecessor3: | Patrick Hughes |
| Successor3: | Riding abolished |
| Term Start3: | 1879 |
| Term End3: | 1882 |
| Office4: | MP for Niagara |
| Predecessor4: | Angus Morrison |
| Successor4: | Patrick Hughes |
| Term Start4: | 1874 |
| Term End4: | 1878 |
| Birth Date: | 25 March 1816 |
| Birth Place: | East Haven, Connecticut |
| Death Date: | 12 March 1888 |
| Death Place: | Ontario, Canada |
Josiah Burr Plumb (25 March 1816 – 12 March 1888) was an American-born Canadian businessman and parliamentarian. Born in East Haven, Connecticut, Plumb immigrated to Canada in 1865 and settled near Niagara Falls, Ontario. Soon thereafter he became active in the Conservative Party of Canada. He was elected three times as a member of parliament for Niagara in the House of Commons of Canada. He was first elected in the Canadian federal election of 1874, but this result was voided, although he successfully defended the seat in a by-election held on 22 December 1874. Although defeated in the 1878 election, he regained his seat in a contested election in 1879.
Following a defeat in 1882 election, he was appointed to the Senate of Canada on 8 February 1883 on the recommendation of Sir John A. Macdonald. He served as Speaker of the Senate from 4 April 1887 – 12 March 1888, upon his death.