| Overbrook Entertainment | Beverly Hills, Los Angeles | 1998 |
| Owens-Illinois | Toledo, Perrysburg | 1903 |
| P.A. Semi | Santa Clara | 2003 |
| Packard Bell | Chatsworth | 1926 |
| Panic Inc. | Portland, Oregon | — |
| Pantone | Carlstadt | 1962 |
| Paper Mate | Oak Brook | 1940 |
| Parametric Technology Corporation | Boston | maio 1985 |
| Paramount Animation | Los Angeles | 2011 |
| Paramount Global Content Distribution | Santa Mônica, Nova Iorque | 1962 |
| Parker Pen Company | Newhaven, Londres | 1888 |
| Participant | Los Angeles | janeiro 2004 |
| Peabody Energy | St. Louis | 1883 |
| Peerless | Cleveland | 1900 |
| Peet's Coffee | Emeryville | 1966 |
| Pegasystems | Cambridge | 1983 |
| Penguin Random House | Nova Iorque | 1 de julho de 2013 |
| Pennsylvania Railroad | Filadélfia | 13 de abril de 1846 |
| PeopleSoft | Pleasanton, Califórnia | 1987 |
| Perdue Farms | Salisbury | 1920 |
| PerkinElmer | Waltham | 1937 |
| Petco | San Diego | 1965 |
| PetSmart | Phoenix | 1986 |
| Philip Morris International | Stamford, Lausana | 1987 |
| Pierce-Arrow | Buffalo | 1870 |
| PIMCO | Newport Beach | 1971 |
| Ping, Inc. | Phoenix | 1959 |
| Pioneer Hi-Bred | Johnston | 1926 |
| Planet Labs | São Francisco | 28 de dezembro de 2010 |
| Plantronics | Santa Cruz | 1961 |
| Playboy Enterprises | Los Angeles | 1953 |
| PlayStation Now | Aliso Viejo | novembro 2008 |
| Plug Power | Latham, Slingerlands | 1997 |
| PNC Financial Services | One PNC Plaza | 1982 |
| Polycom | São José | 1990 |
| Powell's Books | Portland | 1971 |
| Pratt & Whitney | East Hartford | 1925 |
| Precision Manuals Development Group | Alexandria | 1997 |
| Prince Sports | Bordentown | 1970 |
| Pro Wrestling Guerrilla | Sul da Califórnia | 2003 |
| Procter & Gamble | Ohio, Cincinnati | 31 de outubro de 1837 |
| Prometheus Global Media | Nova Iorque | 2009 |
| Providence Equity Partners | 50 Kennedy Plaza | 1989 |
| PRS Guitars | Stevensville | 1985 |
| Prudential Financial | Prudential Headquarters | 1875 |
| Pullman Company | Chicago, Denver | 1927 |
| PVH Corp. | Nova Iorque | 1881 |
| Pyra Labs | São Francisco | 1999 |