| Cencora | Chesterbrook | 2001 |
| Cengage Learning | Stamford | 2000 |
| Cerebras Systems | Sunnyvale, São Francisco | 2016 |
| CF Industries | Deerfield, Deerfield | 1946 |
| CH2M Hill | Meridian | 1946 |
| Charlton Comics | Derby | 1945 |
| Charter Arms | Shelton | 1964 |
| Chase Bank | Nova Iorque | 1799 |
| Chemical Bank | Midland, Nova Iorque | 1954 |
| Chicago Board of Trade | Chicago | 1848 |
| Chicago Mercantile Exchange | Chicago | 1898 |
| Chips and Technologies | Milpitas | 1985 |
| Church & Dwight | Ewing | 1846 |
| Circle | Boston | outubro 2013 |
| Circuit City | Richmond | 1984 |
| Cisco Systems | São José | 1984 |
| CIT Group Incorporated | Nova Iorque | 1908 |
| Citigroup | 388 Greenwich Street | 8 de outubro de 1998 |
| Citizens Financial Group | Providence | 1954 |
| Citrix Systems | Fort Lauderdale | 1989 |
| Claris | Cupertino | 1987 |
| CLS Group | Nova Iorque | 2002 |
| CME Group | Chicago, Londres | 12 de julho de 2007 |
| Coda Automotive | Los Angeles | 2009 |
| Coldwell Banker | Cairo, Madison | 27 de agosto de 1906 |
| Coleco | West Hartford | 1932 |
| Coleman (marca) | Wichita | 1900 |
| Colt's Manufacturing Company | West Hartford | 1855 |
| Combustion Engineering | Stamford | 1912 |
| Comcast | Filadélfia | 28 de junho de 1963 |
| Comitê Nacional Democrata | Washington, D.C. | 1848 |
| Commodore International | West Chester | 10 de outubro de 1958 |
| CommScope | Claremont | 1976 |
| Comodo Group | Clifton | 1998 |
| Concord Music | Beverly Hills | 1973 |
| Consolidated Aircraft | San Diego | 1923 |
| Constellation Brands | Victor | 1945 |
| Control Data Corporation | Bloomington | 1957 |
| Convergys | Cincinnati | 1998 |
| Cooper Tire & Rubber Company | Findlay | 1926 |
| Corteva | Washington, D.C. | 15 de março de 2018 |
| CouchSurfing | São Francisco | 2 de abril de 2003 |
| CoverGirl | Maryland | 1961 |
| Coverity | São Francisco | novembro 2002 |
| Crayola | Forks Township | 1885 |
| Creative Micro Designs | East Longmeadow | 1987 |
| Cricket Wireless | San Diego | 1999 |
| Crosley | Cincinnati | 1937 |