| Company | Estimated Employees | ||
| 1 | Cincinnati Financial Corp. | 2900 | |
| 2 | Mercy Hospital Fairfield | 1200 | |
| 3 | Fairfield City School District | 1100 | |
| 4 | Ohio Casualty Group | 975 | |
| 5 | Medco Health Solutions | 800 | |
| 6 | Koch Foods | 600 | |
| 7 | Tri-County Extended Care | 500 | |
| 8 | Pacific Industries | 450 | |
| 9 | M Bohlke Veneer Co. | 400 | |
| 10 | City of Fairfield | 375 | |