| State: | KY |
| Type: | KY |
| Route: | 309 |
| Map Custom: | yes |
| Map Notes: | KY 309 highlighted in red |
| Length Mi: | 4.872 |
| Length Ref: | [1] |
| Direction A: | South |
| Terminus A: | Mt. Olive Road in rural Obion Co, TN |
| Direction B: | North |
| Terminus B: | and Broadway Street in Hickman |
| Counties: | Fulton |
| Previous Type: | KY |
| Previous Route: | 308 |
| Next Type: | KY |
| Next Route: | 310 |
Kentucky Route 309 (KY 309) is a 4.872adj=midNaNadj=mid state highway in Fulton County, Kentucky, that runs from Mt. Olive Road in rural Obion County, Tennessee, northwest of Woodland Mills immediately south of the Kentucky–Tennessee state line to KY 94 and Broadway Street in Hickman. KY 309 is unlike most state routes, as its first 143feet of mileage is located in Tennessee, making it one of just a few select Kentucky state routes that have mileage in another state.