| Willow Brook | |
| Pushpin Map: | Northamptonshire |
| Pushpin Map Caption: | Location of the mouth within Northamptonshire |
| Subdivision Type1: | Country |
| Subdivision Name1: | England |
| Subdivision Type3: | County |
| Subdivision Name3: | Northamptonshire |
| Source1 Location: | Corby |
| Mouth: | River Nene |
| Mouth Location: | Fotheringhay |
| Mouth Coordinates: | 52.5326°N -0.4081°W |
| Mouth Elevation: | 17m (56feet) |
| River System: | River Nene |
| Basin Size: | 96.2km2 |
| Tributaries Left: | Gretton Brook |
The Willow Brook is a tributary of the River Nene. Its entire course is in the English county of Northamptonshire.
The Willow Brook rises north of Corby where, until 1980, water was extracted for use at Corby Steelworks. It then flows through or near Deene, Bulwick, Blatherwycke, King's Cliffe and Woodnewton and joins the Nene downstream from Fotheringhay.