- Illini Community Hospital
- Illinois Association of Community Action Agencies
- Illinois Association of School Boards
- Illinois Association of School Business Officials
- Illinois College
- Illinois Council of Health System Pharmacists
- Illinois Department of Public Health
- Illinois Health and Hospital Association
- Illinois Health Education Consortium-AHEC
- Illinois Institute of Technology Student Health and Wellness Center
- Illinois Manufacturers Association
- Illinois Secretary of State Organ-Tissue Donor Program
- Illinois Society of Association Executives
- Illinois State University
- Illinois Wesleyan University
- ILPP
- IMA
- Images Plus
- Imaging Concepts of NM
- IMC Global
- IMI Cornelius Inc.
- Immanuel Residences
- Immersion Medical
- Immigrant Resettlement and Cultural Center, Inc.
- IMN Solutions
- Impact America Media
- Impact Imaging
- Impact Solutions, Inc.
- Impella
- Imperial Construction Group, Inc.
- Imperial County
- Imperial Graphics, Inc.
- IMS Companies
- IMS Interactive Media Solutions, LLC
- In Living Stereo, LTD
- Incarnate Word Retirement Community
- Incontinental Hotel Group
- INDEC Systems, Inc.
- Independence Blue Cross
- Independence Community Bank
- Independent Electrical Contractors of New England
- Independent Health
- Independent Healthcare Staffing, Inc.
- Independents, Collins Plaza, Cedar Rapids
- India Community Center of Austin
- Indian Health Service HIS)
- Indian Health Service Yankton Service Unit
- Indian Health Services
- Indian Hills Community College, Health Occupations
- Indian Path Community Hospital