| Official Name: | Lake Seneca, Ohio |
| Settlement Type: | CDP |
| Mapsize: | 250px |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Ohio |
| Subdivision Type2: | County |
| Subdivision Name2: | Williams |
| Subdivision Type3: | Township |
| Unit Pref: | Imperial |
| Population As Of: | 2020 |
| Population Footnotes: | [1] |
| Population Total: | 529 |
| Timezone: | Eastern (EST) |
| Utc Offset: | -5 |
| Timezone Dst: | EDT |
| Utc Offset Dst: | -4 |
| Elevation Ft: | 932 |
| Coordinates: | 41.67°N -84.6442°W |
| Postal Code Type: | ZIP code |
| Blank Name: | FIPS code |
| Blank1 Name: | GNIS feature ID |
| Blank1 Info: | 2633228 |
Lake Seneca is a census-designated place in Williams County, in the U.S. state of Ohio. The population was 529 at the 2020 census.
Lake Seneca had its start in 1966 as a lakeside planned community.[2]