| Windfall Brook | |
| Pushpin Map: | New York |
| Pushpin Map Caption: | Location of the mouth of Windfall Brook |
| Subdivision Type1: | Country |
| Subdivision Name1: | United States |
| Subdivision Type2: | State |
| Subdivision Name2: | New York |
| Subdivision Type4: | County |
| Subdivision Name4: | Delaware |
| Source1 Coordinates: | 42.2056°N -75.2397°W |
| Mouth: | Loomis Brook |
| Mouth Coordinates: | 42.1806°N -75.2355°W[1] |
| Mouth Elevation: | 1378feet |
Windfall Brook is a river in Delaware County, New York. It flows into Loomis Brook south-southwest of the hamlet of Loomis.