| Chicago State University | public educational institution of the United States, public university | — | September 2, 1867 |
| Chicago, Burlington and Quincy Railroad | railway company | Chicago | 1856 |
| Chili's | restaurant chain | Coppell | March 13, 1975 |
| Chips and Technologies | business, enterprise | Milpitas | 1985 |
| Christopher Newport University | public educational institution of the United States, university, open-access publisher | — | 1961 |
| CHS Inc. | business, gas station chain, public company | Inver Grove Heights | 1931 |
| Chuck E. Cheese | indoor play space, restaurant chain, pizzeria chain, public company | Irving | May 17, 1977 |
| Church's Texas Chicken | fast food restaurant chain, restaurant chain | Sandy Springs | April 17, 1952 |
| Cinemark | cinema chain, public company | Plano | 1984 |
| Cinematronics | video game developer | El Cajon | 1975 |
| Cinemaware | video game publisher, video game developer | Burlingame | 1986 |
| Cineworld | cinema chain, public company | London | 1995 |
| Circle | dot-com company, business | Boston | October 2013 |
| Cirrus Aircraft Corporation | aerospace manufacturer | Duluth | 1984 |
| Citgo | business, gas station chain | Houston | 1910 |
| Citigroup | global systemically important bank, holding company, business, enterprise, credit institution, public company | 388 Greenwich Street | October 8, 1998 |
| Citizens Financial Group | bank, business, public company | Providence | 1954 |
| Claire's | retail chain | Hoffman Estates, Illinois | 1961 |
| Clarivate | public company | Philadelphia, London | October 3, 2016 |
| Clarkson University | private not-for-profit educational institution, university | — | 1896 |
| Clemson University | research university, public educational institution of the United States, land-grant university, public university | — | 1889 |
| Clinique Laboratories, LLC | cosmetics, business, subsidiary company | New York | 1968 |
| ClubJenna | television production company, pornographic film studio | Scottsdale | 2000 |
| CME Group | stock exchange, business, enterprise, public company | Chicago, London | July 12, 2007 |
| CNN | news website, film production company, specialty channel, cable news in the United States | CNN Center, New York City | June 1, 1980 |
| Coach | business, enterprise, public company | New York City | 1941 |
| Coastal Carolina University | public educational institution of the United States, university | Conway | 1954 |
| Coda Automotive | business, automobile manufacturer | Los Angeles | 2009 |
| Codecademy | open educational resource, Virtual learning environment, website, business | New York City | 2011 |
| CodeGear | business, enterprise | Scotts Valley, California | 2006 |
| Cognizant Technology Solutions | technology company, enterprise, public company | Teaneck | 1994 |
| Cole Haan | business, subsidiary company, brick and mortar | Greenland | 1928 |
| Coleco | brand, business | West Hartford | 1932 |
| Coleman Company | business | Wichita | 1900 |
| Colgan Air | regional airline | Memphis | 1991 |
| College of William & Mary | public educational institution of the United States, public research university | Williamsburg | 1693 |
| Colorado College | liberal arts college, private not-for-profit educational institution | Colorado Springs | 1874 |
| Colorado Fuel and Iron | business | Colorado | — |
| Columbia Pictures | film production company, film distributor | United States, Culver City | 1918 |
| Columbia University Press | book publisher, nonprofit organization, university press | New York City | 1893 |
| Columbia University Vagelos College of Physicians and Surgeons | graduate school, university, medical school | New York City | 1767 |
| Columbus Museum of Art | nonprofit organization, art museum, movie theater | Columbus | 1931 |
| Comcast | telecommunications company, business, enterprise, public company | Philadelphia | June 28, 1963 |
| CommuteAir | regional airline | Westlake | 1989 |
| Complex | magazine, business | New York City | 2002 |
| Concord | record company, business | Beverly Hills | 1973 |
| Conexant | business, enterprise | Irvine | 1999 |
| Connecticut College | liberal arts college, private not-for-profit educational institution, school | — | 1911 |