| Official Name: | Dayville, Connecticut |
| Settlement Type: | Census-designated place |
| Pushpin Map: | Connecticut#USA |
| Pushpin Label: | Dayville |
| Coordinates: | 41.8458°N -71.8878°W |
| Subdivision Type: | Country |
| Subdivision Type1: | State |
| Subdivision Name1: | Connecticut |
| Subdivision Type2: | County |
| Subdivision Name2: | Windham |
| Subdivision Type3: | Town |
| Subdivision Name3: | Killingly |
| Area Footnotes: | [1] |
| Area Total Km2: | 2.41 |
| Area Land Km2: | 2.41 |
| Area Water Km2: | 0.0 |
| Population As Of: | 2020 |
| Timezone: | Eastern (EST) |
| Utc Offset: | -5 |
| Timezone Dst: | EDT |
| Utc Offset Dst: | -4 |
| Elevation Ft: | 245 |
| Postal Code Type: | ZIP Code |
| Postal Code: | 06241 |
| Area Code: | 860/959 |
| Blank Name: | FIPS code |
| Blank Info: | 09-18990 |
| Blank1 Name: | GNIS feature ID |
| Blank1 Info: | 2805988 |
Dayville is a census-designated place (CDP) in the northwest part of the town of Killingly in Windham County, Connecticut, United States. It is located on the east side of the Fivemile River, 5miles north of Danielson. Interstate 395 passes through the east side of the CDP, leading south to Norwich and north to Auburn, Massachusetts.
Dayville was first listed as a CDP prior to the 2020 census.
The Dayville Historic District occupies at the center of the village.