| West Branch Souhegan River | |
| Pushpin Map: | New Hampshire#USA |
| Pushpin Map Size: | 250 px |
| Subdivision Type1: | Country |
| Subdivision Name1: | United States |
| Subdivision Type2: | State |
| Subdivision Name2: | New Hampshire |
| Subdivision Type3: | County |
| Subdivision Name3: | Hillsborough |
| Subdivision Type4: | Town |
| Subdivision Name4: | New Ipswich |
| Length: | 3.1miles |
| Source1: | Confluence of Pratt Pond Brook and Fox Brook |
| Source1 Location: | New Ipswich |
| Source1 Coordinates: | 42.7369°N -71.8872°W |
| Source1 Elevation: | 320m (1,050feet) |
| Mouth: | Souhegan River |
| Mouth Location: | New Ipswich |
| Mouth Coordinates: | 42.7311°N -71.8464°W |
| Mouth Elevation: | 927feet |
| Tributaries Left: | Stark Brook |
The West Branch of the Souhegan River is a 3.1adj=midNaNadj=mid[1] river in southern New Hampshire in the United States. It is a tributary of the Souhegan River, which flows to the Merrimack River and ultimately to the Gulf of Maine.
The West Branch is located entirely in the town of New Ipswich, New Hampshire. It begins at the junction of Fox Brook and Pratt Pond Brook, southwest of the town center, and flows east through the settlement known as Smithville, ending at its junction with the South Branch of the Souhegan River north of Gibson Four Corners.