| Castellnovo | |
| Settlement Type: | Municipality |
| Pushpin Map: | Spain#Spain Valencia |
| Pushpin Map Caption: | Location of Castellnovo. |
| Coordinates: | 39.8667°N -27°W |
| Subdivision Type: | Country |
| Subdivision Name: |  Spain |
| Subdivision Type1: | Community |
| Subdivision Type2: | Province |
| Subdivision Name2: | Castellón |
| Subdivision Type3: | Comarca |
| Subdivision Name3: | Alto Palancia |
| Government Footnotes: | [1] |
| Leader Party: | PSPV-PSOE |
| Leader Title: | Mayor |
| Leader Name: | Antonio López Gil |
| Unit Pref: | Metric |
| Area Footnotes: | [2] |
| Area Total Km2: | 19.20 |
| Population Footnotes: | [3] |
| Population As Of: | 2023 |
| Population Total: | 888 |
| Population Density Km2: | auto |
| Timezone1: | CET |
| Utc Offset1: | +1 |
| Timezone1 Dst: | CEST |
| Utc Offset1 Dst: | +2 |
| Postal Code: | 12413 |
Castellnovo is a municipality in the comarca of Alto Palancia, Castellón, Valencia, Spain.