| Pinkerton Government Services | Ann Arbor | February 1855 |
| Pioneer Hi-Bred | Johnston | 1926 |
| Pitney Bowes | Stamford | 1920 |
| Plaxo | Sunnyvale | July 2001 |
| Playboy Enterprises | Los Angeles | 1953 |
| PNC Financial Services | One PNC Plaza | 1982 |
| PPG Industries | Pittsburgh | 1883 |
| PR Newswire | Manhattan | March 8, 1954 |
| Pratt & Whitney Rocketdyne | Canoga Park | 2005 |
| Praxair | Danbury | 1907 |
| Precision Manuals Development Group | Alexandria | 1997 |
| Prime Computer | Natick | 1972 |
| Princess Cruises | Santa Clarita | 1965 |
| Pro Wrestling Guerrilla | Southern California | 2003 |
| Prometheus Global Media | New York City | 2009 |
| Providence Equity Partners | 50 Kennedy Plaza | 1989 |
| PRS Guitars | Stevensville | 1985 |
| Quaker Oats Company | Chicago | 1877 |
| Qualcomm | San Diego | July 1985 |
| Qualtrics | Provo | 2002 |
| Quest Software | Aliso Viejo | 1987 |
| QVC | Düsseldorf | 1986 |
| R. J. Reynolds Tobacco Company | Winston-Salem | 1874 |
| Radisson Hotel Group | Minnetonka | 1962 |
| Raising Cane's Chicken Fingers | Baton Rouge | 1996 |
| Ralston Purina | St. Louis | 1894 |
| Ramada | Phoenix | 1953 |
| Rambus | Sunnyvale | 1990 |
| Rawlings | Town and Country | 1887 |
| Razer Inc. | George Town, Singapore, Carlsbad, Irvine, San Francisco | 1998 |
| RC4WD | San Francisco | 2001 |
| RCA Records | New York City | 1901 |
| RE/MAX | Denver | 1973 |
| Real3D | Orlando | 1986 |
| RealNetworks | Seattle | 1993 |
| Realty Income Corporation | San Diego | 1969 |
| Red Digital Cinema Camera Company | Lake Forest | 2005 |
| Red Hat | Raleigh | March 27, 1993 |
| Redback Networks | San Jose | 1996 |
| Redfin | Seattle | 2004 |
| Reebok | Boston | 1895 |
| Regeneron Pharmaceuticals | Eastview | 1988 |
| Regent Seven Seas Cruises | Miami | 1990 |
| Remington Arms | Madison | 1816 |
| Remote Control Productions | Santa Monica | 1989 |
| Republic Airways Holdings | Indianapolis | 1973 |
| Revlon | New York City | 1932 |
| Revolution Studios | Los Angeles | 2000 |