- Established: 1804
- Population: 33,342 (2000 census)
- County Seat: Ovid and Waterloo
- Tourism Region: Finger Lakes
- Information: Seneca County website
- Bordering Counties: Cayuga, Ontario, Schuyler, Tompkins, Wayne, Yates
- Area code: 315
- Incorporated Cities: None
- Villages: Interlaken, Lodi, Ovid, Romulus, Seneca Falls, Waterloo
- Towns: Covert, Fayette, Junius, Lodi, Ovid, Romulus, Seneca Falls, Tyre, Varick, Waterloo
- Seneca County is in NYSDOT Region 3, county code 35.
- List of county highways from Empire State Roads.
- Relevant exit guides: