| West Branch Upper Ammonoosuc 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: | Coos |
| Subdivision Type4: | Township and city |
| Subdivision Name4: | Kilkenny, Berlin |
| Length: | 6.1miles |
| Source1: | Mount Cabot |
| Source1 Location: | Kilkenny |
| Source1 Coordinates: | 44.5083°N -71.4053°W |
| Source1 Elevation: | 3100feet |
| Mouth: | Upper Ammonoosuc River |
| Mouth Location: | Berlin |
| Mouth Coordinates: | 44.4975°N -71.3072°W |
| Mouth Elevation: | 393m (1,289feet) |
| Tributaries Left: | No. 9 Brook, Cold Brook |
| Tributaries Right: | Spring Brook |
The West Branch of the Upper Ammonoosuc River is a 6.1adj=midNaNadj=mid[1] river in northern New Hampshire in the United States. It is a tributary of the Upper Ammonoosuc River and part of the Connecticut River watershed. For most of its length, it is within the White Mountain National Forest.
The West Branch rises in the township of Kilkenny, New Hampshire, in a basin on the east side of Mount Cabot, the highest peak in the Pilot Range. The river flows east into Berlin, passing the Berlin National Fish Hatchery at York Pond before joining the Upper Ammonoosuc River.