| Northumberland—Peterborough South | |
| Province: | Ontario |
| Prov-Status: | active |
| Prov-Created: | 2015 |
| Prov-Election-First: | 2018 |
| Prov-Election-Last: | 2022 |
| Prov-Rep: | David Piccini |
| Prov-Rep-Party: | PC |
| Demo-Census-Date: | 2016 |
| Demo-Pop: | 112415 |
| Demo-Electors: | 94504 |
| Demo-Electors-Date: | 2018 |
| Demo-Area: | 2903 |
| Demo-Cd: | Durham, Northumberland, Peterborough County |
| Demo-Csd: | Alnwick/Haldimand, Brighton, Clarington, Cobourg, Cramahe, Hamilton Township, Otonabee–South Monaghan, Peterborough, Port Hope, Trent Hills |
Northumberland—Peterborough South is a provincial electoral district in Ontario, Canada. It elects one member to the Legislative Assembly of Ontario. The riding was created in 2015.[1]