| Iḷisaġvik College | Alaska |
| Ilium Software | Michigan |
| Illexcor Therapeutics, LLC | |
| ILLFONIC, Inc. | Washington |
| Illiana Financial | |
| ILLICO | California |
| Illinois Central College | Illinois |
| Illinois College | Illinois |
| Illinois Components, Inc. | Illinois |
| Illinois Computer Training | Illinois |
| Illinois Education Association | |
| Illinois Fermentation and Agriculture Biomanufacturing Hub | Illinois |
| Illinois Innovation Network | Illinois |
| Illinois Institute of Technology | Illinois |
| Illinois Institute of Technology Applied Mathematics | Illinois |
| Illinois Institute of Technology College of Computing | Illinois |
| Illinois Institute of Technology Computer Science | Illinois |
| Illinois Institute of Technology Department of Electrical and Computer Engineering | Illinois |
| Illinois Mathematics and Science Academy | Illinois |
| Illinois Mathematics and Science Academy Mathematics and Computer Science | Illinois |
| Illinois Science & Technology Coalition | Illinois |
| Illinois State University | Illinois |
| Illinois State University Center for Mathematical, Science and Technology | Illinois |
| Illinois State University Department of Mathematics | Illinois |
| Illinois State University School of Information Technology | Illinois |
| Illinois Telecommunications Association | Illinois |
| Illinois University Incubator Network | Illinois |
| Illinois Ventures | Illinois |
| Illinois Wesleyan University | Illinois |
| Illinois Wesleyan University Mathematics | Illinois |
| Illinois Wholesale | Illinois |
| Illuma | Texas |
| iLLUME Ai | Colorado |
| Illumedia Outsourcing, Inc. | |
| Illumicell AI | Massachusetts |
| IllumiDesk, LLC | |
| Illumifin | South Carolina |
| Illumina Interactive, Inc. | Massachusetts |
| Illumina, Inc. | California |
| Illuminare Biotechnologies | |
| Illuminate Education | California |
| Illuminate Ventures | California |
| Illuminati Karate | North Carolina |
| Illumination Consulting | California |
| Illuminations Web Services | Tennessee |
| IllumineX, Inc. | District of Columbia |
| IlluminiDesk, LLC | |
| IlluminOss Medical, Inc. | Rhode Island |
| Illumio | California |
| Illustrated Designs, Inc. | |