| Willoughby River | |
| Map Size: | 200 |
| Pushpin Map: | USA Vermont |
| Pushpin Map Size: | 200 |
| Pushpin Map Caption: | Location of mouth within Vermont |
| Subdivision Type1: | Country |
| Subdivision Name1: | United States |
| Subdivision Type2: | State |
| Subdivision Name2: | Vermont |
| Subdivision Type3: | County |
| Subdivision Name3: | Orleans County |
| Length: | 11.6miles |
| Discharge1 Location: | Orlean, Vermont |
| Source1: | Lake Willoughby |
| Source1 Location: | Westmore, Vermont, Orleans County, Vermont, United States |
| Source1 Coordinates: | 44.7481°N -72.0594°W |
| Source1 Elevation: | 1168feet |
| Mouth: | Barton River |
| Mouth Location: | Orleans, Vermont, Orleans County, Vermont, United States |
| Mouth Coordinates: | 44.8175°N -72.2039°W |
| Mouth Elevation: | 715feet |
| Tributaries Left: | Lord Brook |
| Tributaries Right: | Brownington Branch |
The Willoughby River is a tributary of the Barton River, flowing on 18.6km (11.6miles), in the Orleans County, Vermont, United States.
This river flows to northwest, southwest and northwest, crossing the municipalities of Westmore, Vermont, Orleans and Brownington. Its course runs through forested areas, agricultural and urban.
The Willoughby River rises on the northwest shore of Lake Willoughby (length: 6.9km (04.3miles); maximum length: 1.3km (00.8miles); height: 356m (1,168feet)). The southern part of the lake is surrounded by the Willoughby State Forest. This natural park contains the Mount Pisgah, Mount Hor and Mount Bartlett.
From the mouth of the Lake Willoughby, the Willoughby River flows on 18.6km (11.6miles) according to the following segments:
The term "Willoughby" is a surname of English origin.
The English place name "Willoughby River" was made official October 29, 1980 to the GNIS.