| KMKickhaefer Manufacturing Company, LLC | Port Washington | WI | Fabricated Metal Product Manufacturing332116 | 100-499 | ◐ LIKELY ACTIVE |
| KFKirsh Foundry INC | Beaver Dam | WI | Primary Metal Manufacturing331511 | 20-99 | ◐ LIKELY ACTIVE |
| KBKrueger Bearings INC | Milwaukee | WI | Fabricated Metal Product Manufacturing332710 | 20-99 | ◐ LIKELY ACTIVE |
| KLKs Large Bore Pistons INC | Marinette | WI | Machinery Manufacturing333618 | 100-499 | ◐ LIKELY ACTIVE |
| KNKuhn North America INC | Brodhead | WI | Machinery Manufacturing333110 | 100-499 | ◐ LIKELY ACTIVE |
| KEKusel Equipment CO | Watertown | WI | Fabricated Metal Product Manufacturing332913 | 20-99 | ◐ LIKELY ACTIVE |
Lactalis Heritage Dairy, INC. | Wausau | WI | Food Manufacturing311513 | 100-499 | ◐ LIKELY ACTIVE |
| LOLand O Lakes, Kiel, Wi | Kiel | WI | Food Manufacturing311513 | 100-499 | ◐ LIKELY ACTIVE |
| LTLannon Tank CORP | Lannon | WI | Fabricated Metal Product Manufacturing332420 | 20-99 | ◐ LIKELY ACTIVE |
Laserform LLC | De Pere | WI | Fabricated Metal Product Manufacturing332322 | 20-99 | ◐ LIKELY ACTIVE |
| LGLauterbach Group | Sussex | WI | Paper Manufacturing322222 | 20-99 | ◐ LIKELY ACTIVE |
| LPLeader Paper Products, INC. | Milwaukee | WI | Paper Manufacturing322230 | 20-99 | ◐ LIKELY ACTIVE |
| LILiphatech INC. | Milwaukee | WI | Chemical Manufacturing325320 | 20-99 | ◐ LIKELY ACTIVE |
| LMLippmann Milwaukee | Cudahy | WI | Machinery Manufacturing333120 | 20-99 | ◐ LIKELY ACTIVE |
Louisiana Pacific Corporation \2013 Green Bay | Green Bay | WI | Wood Product Manufacturing321219 | 100-499 | ◐ LIKELY ACTIVE |
Louisiana-pacific Corporation-hayward | Hayward | WI | Wood Product Manufacturing321210 | 100-499 | ◐ LIKELY ACTIVE |
| MTMahuta Tool Corp | Germantown | WI | Fabricated Metal Product Manufacturing332710 | 20-99 | ◐ LIKELY ACTIVE |
| MGManitowoc Grey Iron Foundry INC | Manitowoc | WI | Primary Metal Manufacturing331511 | 1-19 | ◐ LIKELY ACTIVE |
| MEMarquis Energy-wisconsin LLC | Necedah | WI | Chemical Manufacturing325193 | — | ◐ LIKELY ACTIVE |
| MCMasterson Company, the | Milwaukee | WI | Food Manufacturing311999 | 100-499 | ◐ LIKELY ACTIVE |
| MMMathison Manufacturing | Waukesha | WI | Fabricated Metal Product Manufacturing332999 | 20-99 | ◐ LIKELY ACTIVE |
| MIMCD, Inc. | Madison | WI | Paper Manufacturing322200 | 20-99 | ◐ LIKELY ACTIVE |
| MPMckinley Paper and Packaging CO | Combined Locks | WI | Paper Manufacturing322120 | 100-499 | ◐ LIKELY ACTIVE |
| MHMenzner Hardwoods CO | Marathon | WI | Wood Product Manufacturing321910 | 100-499 | ◐ LIKELY ACTIVE |
| MTMerrill Tool & Water Jet, LLC | Merrill | WI | Fabricated Metal Product Manufacturing332710 | 20-99 | ◐ LIKELY ACTIVE |
| MNMerz North America INC | Sturtevant | WI | Miscellaneous Manufacturing339113 | — | ◐ LIKELY ACTIVE |
| MOMetalcraft of Mayville-beaver Dam | Beaver Dam | WI | Fabricated Metal Product Manufacturing332322 | 100-499 | ◐ LIKELY ACTIVE |
| MOMetalcraft of Mayville - Fall River | Fall River | WI | Fabricated Metal Product Manufacturing332312 | 100-499 | ◐ LIKELY ACTIVE |
| MIMetalStorm, Inc. | DePere | WI | Fabricated Metal Product Manufacturing332999 | 20-99 | ◐ LIKELY ACTIVE |
| MIMetaltek Intl - Wisconsin Investcast | Watertown | WI | Primary Metal Manufacturing331510 | 100-499 | ◐ LIKELY ACTIVE |
| MFMid-City Foundry Co. - Milwaukee Division | Milwaukee | WI | Primary Metal Manufacturing331510 | 20-99 | ◐ LIKELY ACTIVE |
| MMMidwest Millwork & Casework LLC | La Crosse | WI | Furniture and Related Product Manufacturing337212 | 20-99 | ◐ LIKELY ACTIVE |
| MIMilkrite Interpuls INC | Johnson Creek | WI | Chemical Manufacturing325212 | 100-499 | ◐ LIKELY ACTIVE |
| MTMillennium Technologies LLC | Plymouth | WI | Fabricated Metal Product Manufacturing332710 | — | ◐ LIKELY ACTIVE |
| MFMilwaukee Forgetech INC. | Milwaukee | WI | Primary Metal Manufacturing331111 | 100-499 | ◐ LIKELY ACTIVE |
| MMMilwaukee Metal Products CO | Milwaukee | WI | Fabricated Metal Product Manufacturing332999 | 1-19 | ◐ LIKELY ACTIVE |
| MPMilwaukee Plating CO | Milwaukee | WI | Fabricated Metal Product Manufacturing332810 | 20-99 | ◐ LIKELY ACTIVE |
| MMMiro Mfg., INC | Waukesha | WI | Machinery Manufacturing333517 | 20-99 | ◐ LIKELY ACTIVE |
| MSMixer Systems INC | Pewaukee | WI | Machinery Manufacturing333120 | 20-99 | ◐ LIKELY ACTIVE |
| MBMolecular Biology Resources INC | Milwaukee | WI | Food Manufacturing311930 | 20-99 | ◐ LIKELY ACTIVE |
| MTMorgan Truck Body LLC | Janesville | WI | Transportation Equipment Manufacturing336200 | 100-499 | ◐ LIKELY ACTIVE |
| MIMuthig Industries INC | Fond Du Lac | WI | Fabricated Metal Product Manufacturing332116 | 20-99 | ◐ LIKELY ACTIVE |
| NMNational Manufacturing Group - Franksville | Franksville | WI | Chemical Manufacturing325991 | 20-99 | ◐ LIKELY ACTIVE |
| NPNational Presto Industries INC | Eau Claire | WI | Paper Manufacturing322291 | 100-499 | ◐ LIKELY ACTIVE |
| NCNccm Company LLC | River Falls | WI | Textile Mills313230 | 20-99 | ◐ LIKELY ACTIVE |
| NCNekoosa Coated Products LLC | Nekoosa | WI | Paper Manufacturing322220 | 20-99 | ◐ LIKELY ACTIVE |
| NTNeosho Trompler Inc | Hartland | WI | Fabricated Metal Product Manufacturing332710 | 20-99 | ◐ LIKELY ACTIVE |
| NCNestle Co., INC. | Burlington | WI | Food Manufacturing311320 | 500+ | ◐ LIKELY ACTIVE |
| NBNew Berlin Plastics Incorporated | New Berlin | WI | Plastics and Rubber Products Manufacturing326199 | 100-499 | ◐ LIKELY ACTIVE |
| NPN.e.w. Plastics CORP. | Luxemburg | WI | Plastics and Rubber Products Manufacturing326160 | 100-499 | ◐ LIKELY ACTIVE |