| Martin Marietta | Bethesda | 1961 |
| Masdar | Abu Dhabi | April 2006 |
| Masten Space Systems | Mojave | 2004 |
| Mastercard | Purchase | 1966 |
| Match Group | Kerrville | 2009 |
| Matson, Inc. | Honolulu | 1882 |
| Maxwell Technologies | San Diego | 1965 |
| Maytag | — | 1893 |
| McIntosh Laboratory | Binghamton, New York City | 1949 |
| Mead Johnson | Glenview | 1905 |
| Memorex | Cerritos | 1961 |
| Mentholatum | Orchard Park | 1889 |
| Mentor Graphics | Wilsonville | 1981 |
| Merck & Co. | Rahway | 1891 |
| Meredith Corporation | Des Moines | 1902 |
| Merrell | Rockford | 1981 |
| Merrill | New York City | January 6, 1914 |
| Meta Platforms | Menlo Park | July 29, 2004 |
| MetLife | New York City | March 24, 1868 |
| Metro Pictures | Los Angeles | 1915 |
| Metro-Goldwyn-Mayer | Los Angeles | April 17, 1924 |
| MFS Investment Management | Boston | 1924 |
| MGM Holdings | Beverly Hills | February 11, 2005 |
| Micro Instrumentation and Telemetry Systems | Albuquerque | 1970 |
| Micron Technology | Boise | October 1978 |
| Middle-earth Enterprises | Berkeley | 2022 |
| Mobil | Fairfax | 1966 |
| Moderna | Cambridge | 2010 |
| Modulus Graphite | Richmond | 1978 |
| Monster.com | Guaynabo | 1999 |
| Moog Music | Asheville | 1953 |
| Morgan Stanley | New York City | 1931 |
| MOS Technology | Norristown | 1969 |
| Mosrite | Arizona | 1956 |
| Motorola Solutions | Chicago | January 4, 2011 |
| MSA Safety | Pittsburgh, Cranberry Township | 1914 |
| MSCI | New York City | 1969 |
| Namesys | Oakland | 2004 |
| National Geographic Partners | New York City | September 9, 2015 |
| National Instruments | Austin | 1976 |
| National Wrestling Alliance | Houston | 1948 |
| Nationwide Mutual Insurance Company | One Nationwide Plaza | 1926 |
| Nautica | New York City | 1983 |
| NCR Corporation | Atlanta, Augsburg | 1884 |
| Neiman Marcus | Dallas | 1907 |
| NetApp | Sunnyvale | 1992 |
| Netflix, Inc. | Los Gatos | August 29, 1997 |
| NetJets | Columbus | 1964 |