| Castellfollit del Boix | |
| Settlement Type: | Municipality |
| Pushpin Map: | Spain Province of Barcelona#Spain |
| Pushpin Map Caption: | Location in Catalonia |
| Coordinates: | 41.6658°N 1.6847°W |
| Subdivision Type: | Country |
| Subdivision Name: |  Spain |
| Subdivision Type1: | Community |
| Subdivision Type2: | Province |
| Subdivision Name2: | Barcelona |
| Subdivision Type3: | Comarca |
| Subdivision Name3: | Bages |
| Leader Title: | Mayor |
| Leader Name: | Celestí Rius Prat (2015)[1] |
| Unit Pref: | Metric |
| Area Footnotes: | [2] |
| Area Total Km2: | 58.9 |
| Population As Of: | 2022 |
| Population Footnotes: | [3] |
| Population Total: | 460 |
| Population Density Km2: | auto |
Castellfollit del Boix (in Catalan; Valencian pronounced as /kəsˌteʎfuˈʎid dəl ˈβoʃ/) is a village in the province of Barcelona and autonomous community of Catalonia, Spain. The municipality covers an area of and the population in 2014 was 460.[3]