| Century 21 Real Estate | Madison | 1971 |
| Cerebras Systems | Sunnyvale, São Francisco | 2016 |
| Champ Car | — | 1979 |
| Chemical Bank | Midland, Nova Iorque | 1954 |
| Chicago Board of Trade | Chicago | 1848 |
| Chicago Mercantile Exchange | Chicago | 1898 |
| Choice Hotels | Rockville, Silver Spring | 1939 |
| Circuit City | Richmond | 1984 |
| CIT Group Incorporated | Nova Iorque | 1908 |
| Citgo | Houston | 1910 |
| Citibank | Sioux Falls, Nova Iorque | 1865 |
| Clinique | Nova Iorque | 1968 |
| CLS Group | Nova Iorque | 2002 |
| CME Group | Chicago, Londres | 12 de julho de 2007 |
| Coach New York | Nova Iorque | 1941 |
| Coda Automotive | Los Angeles | 2009 |
| Codecademy | Nova Iorque | 2011 |
| CodeGear | Scotts Valley, Califórnia | 2006 |
| Cognex Corporation | Natick | 1981 |
| Coleco | West Hartford | 1932 |
| Coleman (marca) | Wichita | 1900 |
| Color Force | West Hollywood | 2007 |
| Colorado Fuel and Iron | Colorado | — |
| Colt's Manufacturing Company | West Hartford | 1855 |
| Combat Zone Wrestling | Filadélfia | 1998 |
| Combustion Engineering | Stamford | 1912 |
| Comcast | Filadélfia | 28 de junho de 1963 |
| Commodore International | West Chester | 10 de outubro de 1958 |
| Commonwealth Fusion Systems | Devens | 2018 |
| Compaq | Houston | 16 de fevereiro de 1982 |
| Compuserve | Columbus | 1969 |
| Conair | East Windsor Township | 1959 |
| Concentrix | Fremont | 2004 |
| ConocoPhillips | Houston | 1875 |
| Consol Energy | Pittsburgh | 1991 |
| Consolidated Aircraft | San Diego | 1923 |
| Consolidated Edison | Manhattan | 1 de janeiro de 1998 |
| Constellation Brands | Victor | 1945 |
| Converse | Boston | 1910 |
| CoreWeave | Roseland | 2017 |
| Corning Inc. | Corning | 1851 |
| Corporation for Public Broadcasting | Washington, D.C. | 7 de novembro de 1967 |
| Costco | Issaquah | 1983 |
| Coty | Nova Iorque | 1904 |
| CoverGirl | Maryland | 1961 |
| Coverity | São Francisco | novembro 2002 |
| Cox Communications | Phoenix | 1962 |
| Crayola | Forks Township | 1885 |