| Illinois State University IL | Educational Services | 4 | $90,660 | — |
| Illinois State Wildlife Service IL | Agriculture & Forestry | 0 | — | A |
| ILLINOIS TOOL WOLKS INC MI | — | 0 | — | — |
| Illinois Tool Works AR | Manufacturing | 0 | — | A |
| Illinois Tool Works CA | Manufacturing | 0 | — | A |
| Illinois Tool Works CT | Manufacturing | 0 | — | A |
| Illinois Tool Works FL | Professional & Technical Services | 0 | — | A |
| Illinois Tool Works GA | Manufacturing | 0 | — | A |
| Illinois Tool Works IA | Manufacturing | 0 | — | C |
| Illinois Tool Works MI | Manufacturing | 0 | — | D |
| Illinois Tool Works MN | Manufacturing | 0 | — | A |
| Illinois Tool Works MO | Manufacturing | 0 | — | B |
| Illinois Tool Works MS | Wholesale Trade | 0 | — | A |
| Illinois Tool Works NJ | Manufacturing | 0 | — | F |
| Illinois Tool Works TN | Manufacturing | 0 | — | F |
| Illinois Tool Works WI | Manufacturing | 0 | — | F |
| Illinois Tool Works Inc. IL | Manufacturing | 15 | $106,320 | F |
| Illinois Tool Works Inc. MA | Manufacturing | 1 | $118,227 | D |
| ILLINOIS TOOL WORKS INC. NY | Manufacturing | 0 | — | F |
| Illinois Valley Community College IL | Educational Services | 0 | — | A |
| Illinois Wesleyan University IL | Educational Services | 7 | $75,437 | — |
| Illiopolis Volunteer Fire Department IL | Public Administration | 0 | — | A |
| Illlinois Foundation Seeds Inc IL | Agriculture & Forestry | 0 | — | F |
| Illum Horticulture, LLC AZ | Manufacturing | 0 | — | A |
| Illume MN | Manufacturing | 0 | — | A |
| Illume Ag HR, Inc. CA | — | 0 | — | — |
| Illume Agriculture, LLC CA | Agriculture & Forestry | 0 | — | D |
| Illume Candles LLC MN | — | 0 | — | — |
| Illumifin Corporation MN | Finance & Insurance | 3 | $129,172 | — |
| Illumina WI | Manufacturing | 0 | — | A |
| Illumina Inc. World Headquarters CA | — | 0 | — | — |
| Illumina Technology Solutions, LLC OR | Professional & Technical Services | 3 | $145,333 | — |
| Illumina, Inc Worldwide Headquarters CA | — | 0 | — | — |
| Illumina, Inc. CA | Professional & Technical Services | 39 | $148,602 | C |
| Illumina, Inc. Worldwide Headquarters CA | — | 0 | — | — |
| Illumina-Foster City CA | Professional & Technical Services | 0 | — | A |
| Illumina-Hayward CA | Manufacturing | 0 | — | B |
| Illuminate HC MI | Healthcare & Social Assistance | 0 | — | F |
| Illuminate Operations VA | Professional & Technical Services | 0 | — | A |
| Illuminate USA LLC OH | Manufacturing | 2 | $101,621 | A |
| Illuminations by Greenlee TX | Construction | 0 | — | F |
| Illuminus WI | Healthcare & Social Assistance | 0 | — | F |
| Illumio, Inc. CA | Professional & Technical Services | 14 | $184,873 | — |
| ILLUMUS FL | — | 0 | — | — |
| ILM Properties, LLC CO | Construction | 0 | — | F |
| ILMO Products Company IL | Manufacturing | 0 | — | A |
| Ilmor Engineering MI | Manufacturing | 0 | — | C |
| Ilmor Marine NC | Manufacturing | 0 | — | A |
| ILOGIC TEK , L.L.C MA | Professional & Technical Services | 4 | $113,332 | — |
| ILOGIC, INC. NJ | Professional & Technical Services | 8 | $107,534 | — |
