| Netlify | San Francisco | January 27, 2014 |
| NetSuite | Austin | 1998 |
| New York Mercantile Exchange | New York City | 1872 |
| Newegg | City of Industry | 2001 |
| Nik Software | San Diego | 1995 |
| Nike | Beaverton | January 25, 1964 |
| Nomura Securities Co Ltd | Nihonbashi, Tokyo | May 7, 2001 |
| Nordstrom | Seattle | 1901 |
| Norwegian Cruise Line | Miami-Dade County | 1966 |
| Nucor | Charlotte | September 1955 |
| NZXT | Los Angeles | 2004 |
| O'Reilly Auto Parts | Springfield | 1957 |
| O.F. Mossberg & Sons | North Haven | 1919 |
| Oberheim Electronics | Oakland | 1969 |
| Obsidian Entertainment | Irvine | June 12, 2003 |
| Occidental Petroleum | Houston | 1920 |
| Ocean Spray | Lakeville | 1930 |
| Office Depot | Boca Raton | 1986 |
| OfficeMax | — | 1988 |
| Old Navy | San Francisco | 1994 |
| Olin Corporation | Clayton | 1892 |
| ONErpm | Brooklyn | 2010 |
| Oneworld | Fort Worth | 1999 |
| Open Invention Network | Durham, New York City | November 10, 2005 |
| OpenDNS | San Francisco | July 2006 |
| OQO | San Francisco | 2000 |
| Orion Pictures | Los Angeles | January 1978 |
| Oscar Mayer | Chicago | 1883 |
| Oshkosh Corporation | Oshkosh | 1917 |
| Otis Worldwide Corporation | Farmington | 1853 |
| Ovation Guitar Company | New Hartford | 1966 |
| Overbrook Entertainment | Beverly Hills, Los Angeles | 1998 |
| Pacific Data Images | Redwood City | 1980 |
| Packard Bell | Chatsworth | 1926 |
| Palm, Inc. | Sunnyvale | 1992 |
| Pan Am | New York City | March 14, 1927 |
| Panic | Portland, Oregon | — |
| Paper Mate | Oak Brook | 1940 |
| Parametric Technology Corporation | Boston | May 1985 |
| Parker Brothers | Beverly, Salem | 1883 |
| Participant | Los Angeles | January 2004 |
| Patagonia, Inc. | Ventura | 1973 |
| Peavey Electronics | Meridian | 1965 |
| Penguin Random House | New York City | July 1, 2013 |
| Pennsylvania Railroad | Philadelphia | April 13, 1846 |
| Penske Media Corporation | Los Angeles | 2004 |
| Perdue Farms | Salisbury | 1920 |
| PerkinElmer | Waltham | 1937 |