I
| ID Visuals | Glendale |
| IIS | Madison |
| Imaging Communication Services | Milwaukee |
| Imagiware, Inc. | Madison |
Fond du Lac | |
| Impact Consulting Group | Brookfield |
| Indus International, Inc. | West Salem |
| Industrial Multimedia and Video | Waukesha |
| InfoCor Communications Company | Milwaukee |
| Inland Printing Company | La Crosse |
| Insurance & Financial Services (IFS) | Greenfield |
| Integrated Office Solutions | New Berlin |
| IntelliCAM Custom Products Corp. | Greenville |
| Intelligent Networks, Inc. | Madison |
| Inter Lake Papers, Inc., A Co. Of Consolidated Papers, Inc. | Kimberly |
| Interactive Media Solutions | Madison |
| Intergreen Computing | Mt. Horeb |
| International Thermal Systems, LLC | Milwaukee |
| Invensys Power Systems | Necedah |
| Invincible Office Furniture | Manitowoc |
| Inwave | Janesville |
| INX International Ink Co. | Milwaukee |
| Ironye Productions, Inc. | Glendale |
| Isthmus Publishing Company, Inc. | Madison |
| ITerra Group | Milwaukee |
| ITW Bee Leitzke | Iron Ridge |
| Izzy B Deals | Oregon |
J
| Jacobs Archival Services | Madison |
| J.J. Keller & Associates, Inc. | Neenah |
| Jacobsen Div., Textron Inc. | Racine |
| JADE Technologies, Inc. | Brookfield |
| Janesville Tool & Manufacturing, Inc | Milton |
| Janssen Accounting & Tax Services, Inc. | Waupaca |
| Jansson, Shupe & Munger, Ltd. | Racine |
| JARP Industries, Inc. | Wausau |
| Jason Inc. | Milwaukee |
| JBI Spray Booths & Ovens | Osseo |
| JEAH Communications, LLC | Milwaukee |
| JG Development, Inc. | Blue Mounds |
| Jibangus, LLC | Monona |
| Jockey International, Inc. | Kenosha |
| John C. Cabaniss, Attorney at Law | Milwaukee |
| Johnson Brass & Machine Foundry, Inc. | Saukville |
| Johnson Controls Inc | Milwaukee |
| Johnson Electric Coil Co. | Antigo |
| Johnson Insurance | Racine |
| Johnson & Johnson Land Co. | Cumberland |
| Johnson Outdoors Inc | Sturtevant |
| Johnson Truck Bodies | Rice Lake |
| Jorgensen Conveyors, Inc. | Mequon |
| Joseph L. Bollig & Sons, Inc. | Mauston |
| Joy Global Inc | Milwaukee |
| JP Schoemer Communicatons | Sheboygan |
| J-Star Industries | Fort Atkinson |
| JVLNet | Janesville |
| JWC Building Specialties, Inc. | Waukesha |
