K
| K23 Enterprises | Medford |
| K2 Sourcing, Inc. | Belgium |
| K&L Services | |
| Kahlenberg Brothers Co. | Two Rivers |
| Kahler Slater | Milwaukee |
| Kalmbach Publishing Co. | Waueksha |
| Kasten & Co. | |
| Katarinic & Hollinger, LLC | Milwaukee |
| KCC Corporate, Inc. | Franklin |
| Kempsmith Machine Company | Milwaukee |
| Kewaunee Engineering Corp. | Kewaunee |
| KI | Green Bay |
| Kilgust Mechanical, Inc. | Madison |
| Kimberly-Clark | |
| Kirk Schutte Consulting | Madison |
| Kish and Sons Electric, Inc. | La Crosse |
| Klein Internet Marketing, Inc. | Sussex |
| KMC Stampings | Port Washington |
| Knupp & Watson, Inc. | Madison |
| Kohler Co. | Kohler |
| Kohl’s Corp | Menomonee Falls |
| Kolb Lauwasser & Co. | Milwaukee |
| Kolbe & Kolbe Millwork Co., Inc. | Wausau |
| Kolpak | River Falls |
| Konopacki Design | Sun Prairie |
| Koss Corporation | Milwaukee |
| Kraft Pizza Co. | Milwaukee |
| Krones, Inc. | Franklin |
| Krueger Sentry Gauges | Green Bay |
| Kryson Technologies | Middleton |
| Kusel Equipment Co. | Watertown |
L
| L&L Associates | Mukwonago |
| L&L Metal Finishing | Menomonee |
| L.A. Photography | Cottage Grove |
| Ladish Co., Inc. | Cudahy |
| Lake Monitors, Inc. | Milwaukee |
| Lakeside Foods, Inc. | Manitowoc |
| Lamers Bus Line | |
| Lands’ End | Dodgeville |
| Lappen Security Products | Little Chute |
| Laser Products Technologies, Inc. | Holmen |
| LaserHosts Web Services | DeForest |
| La Bella Vita | Middleton |
| La Tona Time & Sound | Milwaukee |
| Laughing Cat Records | Fort Atkinson |
| Laughlin/Constable | Milwaukee |
| The Law Offices of Paul A. Maranan, S.C. | Cudahy |
| Layer One Media, Inc. | Milwaukee |
| Layton Fruit Market | Milwaukee |
| Leach Co. | Oshkosh |
| Life Style Staffing | Madison |
| Lindsay, Stone, and Briggs | Madison |
| Linetec | Wausau |
| Lippert Corporation | Menomonee |
| Little Rapids Corporation | Green Bay |
| LOCUS, Inc. | Madison |
| Logosmiths | Fredonia |
| LRS Marketing | Milwaukee |
| Lube Devices, Inc. | Manitowoc |
| Lucas-Milhaupt, Inc. | Cudahy |
| Lube Devices, Inc. | Manitowoc |
