| California State University San Marcos | public educational institution of the United States, university | — | 1989 |
| California State University, Bakersfield | public educational institution of the United States, university | Bakersfield | 1965 |
| California State University, Chico | public educational institution of the United States, public university | Chico | 1887 |
| California State University, Dominguez Hills | public educational institution of the United States, university | Carson | 1960 |
| California State University, Long Beach | public educational institution of the United States, public university | Long Beach | 1949 |
| California State University, Northridge | public educational institution of the United States, public university | Los Angeles | 1958 |
| California State University, Sacramento | public educational institution of the United States, university | Sacramento | 1947 |
| California State University, Stanislaus | public educational institution of the United States, university | — | 1957 |
| Callaway Golf Company | organization, business, public company | Carlsbad | 1982 |
| Calvin University | church college, private not-for-profit educational institution, university | East Grand Rapids | 1876 |
| Cambridge Analytica | business, enterprise | London | 2014 |
| Campbell University | private not-for-profit educational institution, university | — | 1887 |
| Canadian Solar | business, public company | — | 2001 |
| Canisius University | private not-for-profit educational institution, university | Buffalo | 1870 |
| Cannondale Bicycle Corporation | bicycle manufacturer, brand, business | Bethel | 1971 |
| Cape Air | airline | Hyannis | 1989 |
| Capital Group Companies | business, enterprise | Los Angeles | 1931 |
| Carhartt | business, enterprise | Dearborn | 1889 |
| Carleton College | liberal arts college, private not-for-profit educational institution | Northfield | 1866 |
| Carlson Wagonlit Travel | business | Minneapolis | 1994 |
| CarMax | business, public company | Goochland County | 1993 |
| Carnegie Mellon University | research university, private not-for-profit educational institution, private university | Pittsburgh | 1900 |
| Carnegie Steel Company | enterprise | Pittsburgh | 1892 |
| Carnival Corporation | business, dual-listed company, public company, cruise line | Doral, Southampton, Florida, London, Miami | 1972 |
| Carroll Shelby International | automobile manufacturer | Enterprise | August 17, 1962 |
| Carroll University | liberal arts college, private not-for-profit educational institution, private university | Waukesha | 1846 |
| Cartercar | business, automobile manufacturer | Pontiac | 1905 |
| Case Corporation | brand, business | United States | 1842 |
| Castle Rock Entertainment | television production company, film production company | Beverly Hills | June 19, 1985 |
| Catholic News Service | news agency | — | 1920 |
| Cavedog Entertainment | video game developer | Bothell | 1996 |
| CBGB | nightclub, music venue | — | 1973 |
| CBS | radio network, television network | CBS Building | September 18, 1927 |
| CBS Films | film production company, film distributor | Los Angeles | March 2007 |
| CD Baby | media distributor, independent record label, record label, online music store | Portland | 1997 |
| Cecil H. Green Library | academic library, library building | Stanford | 1919 |
| Celera Corporation | business | Rockville, Alameda | May 1998 |
| Celgene | pharmaceutical company, business, enterprise, public company | Summit | 1986 |
| Cencora | business, enterprise, public company | Chesterbrook | 2001 |
| Charles Scribner's Sons | publishing house | New York City | 1846 |
| Charter Arms | business | Shelton | 1964 |
| Charter Oak State College | public educational institution of the United States, university | — | 1973 |
| Chase Bank | bank, business | New York City | 1799 |
| Chateau Marmont | hotel | — | 1927 |
| Chautauqua Airlines | airline | Indianapolis | 1973 |
| Chegg | dot-com company, technology company, public company | Santa Clara | 2005 |
| Chemical Abstracts Service | information system, publishing house | Columbus | 1907 |
| Chemical Bank | business | Midland, New York City | 1954 |