| Mad Catz | San Diego | 1989 |
| Mailchimp | Ponce City Market | 2001 |
| Malwarebytes | Santa Clara | 21 de janeiro de 2008 |
| Manhattan Company | The Trump Building | 1799 |
| Marmot | Santa Rosa | 1974 |
| Marriott Internacional | Bethesda | 8 de outubro de 1993 |
| Martin Marietta | Bethesda | 1961 |
| Marvell Technology | Santa Clara | 1995 |
| Mastercard | Purchase | 1966 |
| MasterClass | São Francisco | 2015 |
| Match Group | Kerrville | 2009 |
| Matson, Inc. | Honolulu | 1882 |
| Maytag | — | 1893 |
| McAfee | Santa Clara, São José | 1987 |
| Mead Johnson | Glenview | 1905 |
| Meade Instruments | Irvine | 1972 |
| Mentor Graphics | Wilsonville | 1981 |
| Meraki | São Francisco | 2006 |
| Mercer Automobile Company | New Britain | 1909 |
| Merck Sharp and Dohme | Rahway | 1891 |
| Meredith Corporation | Des Moines | 1902 |
| Merrell | Rockford | 1981 |
| Meta | Menlo Park | 29 de julho de 2004 |
| Metro Pictures Corporation | Los Angeles | 1915 |
| MFS Investment Management | Boston | 1924 |
| MGM Holdings | Beverly Hills | 11 de fevereiro de 2005 |
| MGM Television | Beverly Hills | 1956 |
| Micro Instrumentation and Telemetry Systems | Albuquerque | 1970 |
| Microchip Technology | Chandler | 1989 |
| Middle-earth Enterprises | Berkeley | 2022 |
| Missouri Pacific Railroad | St. Louis | 1917 |
| Moderna Therapeutics | Cambridge | 2010 |
| Mondo Mini Shows | São Francisco | 1988 |
| MoneyGram | Dallas | 1940 |
| Monster Beverage | Minnesota | 1935 |
| Monster Inc. | Brisbane | 1978 |
| Moody's Investors Service | World Trade Center 7 | 1909 |
| Moog Music | Asheville | 1953 |
| Mopar | Chrysler Headquarters and Technology Center | 1933 |
| Morgan Stanley | Nova Iorque | 1931 |
| MOS Technology | Norristown | 1969 |
| Mosrite | Arizona | 1956 |
| Motorola | Schaumburg | 25 de setembro de 1928 |
| MSCI | Nova Iorque | 1969 |
| MUFG Union Bank | São Francisco | 1864 |
| Mutual Film Corporation | Edendale | julho 1906 |
| Narus | Sunnyvale | 1997 |
| Nash Motors | Kenosha | 1914 |