| Citizens Financial Group | Providence | 1954 |
| Clinique Laboratories, LLC | New York | 1968 |
| CME Group | Chicago, London | July 12, 2007 |
| Coach | New York City | 1941 |
| Coda Automotive | Los Angeles | 2009 |
| Codecademy | New York City | 2011 |
| CodeGear | Scotts Valley, California | 2006 |
| Cole Haan | Greenland | 1928 |
| Coleco | West Hartford | 1932 |
| Coleman Company | Wichita | 1900 |
| Colorado Fuel and Iron | Colorado | — |
| Comcast | Philadelphia | June 28, 1963 |
| Complex | New York City | 2002 |
| Concord | Beverly Hills | 1973 |
| Conexant | Irvine | 1999 |
| ConocoPhillips | Houston | 1875 |
| Consol Energy | Pittsburgh | 1991 |
| Constellation Brands | Victor | 1945 |
| Cooper Tire & Rubber Company | Findlay | 1926 |
| Coors Brewing Company | Golden | 1873 |
| Corning Inc. | Corning | 1851 |
| Corteva | Washington, D.C. | March 15, 2018 |
| Costco | Issaquah | 1983 |
| Coty | New York City | 1904 |
| CouchSurfing | San Francisco | April 2, 2003 |
| CoverGirl | Maryland | 1961 |
| Crayola LLC | Forks Township | 1885 |
| Creative Micro Designs | East Longmeadow | 1987 |
| Credo Reference | Boston | 1999 |
| Cricket Wireless | San Diego | 1999 |
| Crosley | Cincinnati | 1937 |
| CrossFit | Santa Cruz | 2000 |
| Crunchbase | San Francisco | July 2007 |
| CSX Corporation | CSX Transportation Building | November 1, 1980 |
| Cummins | Columbus | 1919 |
| Currier and Ives | New York City | 1835 |
| Curtiss-Wright | Charlotte | 1929 |
| CVS Health | Rhode Island, Woonsocket | 1963 |
| Cyan Worlds | Wilmington, Mead | 1987 |
| Cygnus Solutions | — | November 13, 1989 |
| Cyrix | Richardson | 1988 |
| Dallas Semiconductor | Dallas | February 1, 1984 |
| Danelectro | Camarillo | 1947 |
| Danjaq | Santa Monica | 1962 |
| Darden Restaurants | Orange County | 1968 |
| Datapoint | — | 1968 |
| DC Universe | Burbank | 2018 |
| Deckers Outdoor Corporation | Goleta | 1973 |