| Official Name: | Flo Parish |
| Native Name: | Flo socken |
| Settlement Type: | Parish (socken) |
| Unit Pref: | Metric |
| Area Total Km2: | 64.08 |
| Population As Of: | 2000 |
| Population Total: | 434 |
Flo (Swedish: Flo socken) is a historic parish (socken) in the Swedish province of Västergötland. Since 1971 it has been a part of Grästorp Municipality.
Flo parish is the namesake for the Floian stage, which is the second stage of the Lower Ordovician.[1] The base of the Floian is defined at the Diabasbrottet quarry type section (GSSP) 5 km to the northwest of Flo. The base is defined in the quarry as the lowest stratigraphic occurrence of the graptolite species Tetragraptus approximatus.[2]