- Iron Mountain
- Iron Mountain Secure Shredding
- Iron School District
- Iron Workers, Local 17
- Iroquois Memorial Hospital
- Iroquois-Kankakee Regional Office of Education I-KAN)
- Irving Convention and Visitors Bureau
- ISG Plate, Inc.
- ISG Solutions
- Isgrig Financial Service
- Island Press
- Island Systems-Paquito and Sons, Inc.
- Isle of Wight Co.
- Ismart LLC
- ISProductions
- It's Never 2 Late
- Italy-America Chamber of Commerce of Texas Inc.
- ITNS
- ITNS International Transplant Nurses Society)
- ITS America
- ITW Shakeproof Automative
- IU Health Arnett Hospital
- IU Health Ball Memorial Hospital
- IU Health Bedford Hospital
- IU Health Bloomington
- IU Health Methodist Hospital
- IU Health North Hospital
- IU Health Paoli Hospital
- IU Health Saxony Hospital
- IU Health Tipton Hospital
- IU Health University Hospital
- IU Health West Hospital
- IU Health White Memorial Hospital
- Ivinson Memorial Hospital
- IVS Associates
- Iwaniec Associates, Inc.
- IWANNA, Inc.
- J and J Snack Foods Corp
- J Schlegel Marketing Inc.
- J. Brandt Co.,Inc.
- J. Crew Group
- J. Rolfe Davis Insurance
- J. Sargeant Reynolds Community College
- J. Spargo and Associates
- J. T. Rhodes, CPA
- J. Torres Company
- J. Tyler Services Inc.
- J.C. Blair Memorial Hospital
- J.C. Clegg Public Library
- J.F. Ahern Company