| Province: | NL |
| Type: | NL |
| Route: | 91 |
| Alternate Name: | Old Placentia Highway |
| Maint: | Newfoundland and Labrador Department of Transportation and Infrastructure |
| Length Km: | 48 |
| Direction A: | East |
| Terminus A: | at St. Catherine's |
| Junction: |
|
| Direction B: | West |
| Terminus B: | at Southeast Placentia |
| Previous Type: | NL |
| Previous Route: | 90 |
| Next Type: | NL |
| Next Route: | 92 |
Route 91, also known as Old Placentia Highway, is a 48adj=midNaNadj=mid east–west highway located on the Avalon Peninsula in the Canadian province of Newfoundland and Labrador. The highway starts at a junction at Route 90, traveling through the town of Colinet on a paved road, then transitions to a dirt road just west of the Route 92 junction, only to transition back to a paved road prior to approaching its western terminus, Southeast Placentia, where it intersects with Route 100. Along the stretch of dirt road is Cataracts Provincial Park, one of only a small number of active provincial parks remaining since 1997.