| KeyBank | Cleveland | 1825 |
| Keystone Studios | Edendale | 1912 |
| King of the Cage | Rancho Cucamonga | 1998 |
| Kirby Company | Cleveland | 1914 |
| Kodak | Rochester, Nueva York | 1882 |
| Kohl's | Menomonee Falls | 1962 |
| Koss | Milwaukee | 1953 |
| Kraft Heinz | Pittsburgh | 2015 |
| Kroger | Cincinnati | 1882 |
| La-Z-Boy | Monroe | 1927 |
| Lam Research | Fremont | 1980 |
| Landmark Education | San Francisco | 1991 |
| Lay's | — | 1934 |
| Lazard | Nueva York | 12 de julio de 1848 |
| Lear Corporation | Southfield | 1917 |
| Leatherman | Portland | 1983 |
| Leidos | Reston | 1969 |
| Lennox International | Richardson | 1999 |
| Level 3 Communications | Fráncfort del Meno | 1985 |
| Linden Lab | San Francisco | 1999 |
| Lionbridge | Waltham | 1996 |
| Lionel Corporation | Nueva York | 1900 |
| Lionsgate Television | North Vancouver | julio 1997 |
| Lowepro | Petaluma | 1967 |
| M&T Bank | Búfalo | 1856 |
| Mack Trucks | Allentown, Greensboro | 1900 |
| Magpul | — | — |
| Mailchimp | Ponce City Market | 2001 |
| Major League Soccer | Pennsylvania Plaza | 17 de diciembre de 1993 |
| Makerbot | Nueva York | 20 de enero de 2009 |
| Malpaso Productions | Burbank | 1967 |
| MapQuest | Denver | 1967 |
| Marathon Oil | Houston | 1887 |
| Mark Levinson | Estados Unidos | 1972 |
| Marmot | Santa Rosa | 1974 |
| Marriott International | Bethesda | 8 de octubre de 1993 |
| Marsh & McLennan Companies | Nueva York | 1905 |
| Marvell Technology | Santa Clara | 1995 |
| Masdar | Abu Dhabi | abril 2006 |
| Massey Ferguson | Duluth | 1953 |
| MassMutual | Springfield | 1851 |
| MasterClass | San Francisco | 2015 |
| Match Group | Kerrville | 2009 |
| Matson, Inc. | Honolulu | 1882 |
| Maxwell Technologies | San Diego | 1965 |
| McAfee | Santa Clara, San José | 1987 |
| McDonald's | Chicago | 15 de mayo de 1940 |
| McGraw-Hill Education | Nueva York | 1888 |