| California State University, East Bay | public educational institution of the United States, university | Hayward | 1957 |
| California State University, Fresno | public educational institution of the United States, university | Fresno | 1911 |
| California State University, Northridge | public educational institution of the United States, public university | Los Angeles | 1958 |
| California State University, San Bernardino | public educational institution of the United States, university, Hispanic-serving institution | San Bernardino | 1965 |
| Calvin University | church college, private not-for-profit educational institution, university | East Grand Rapids | 1876 |
| Cambridge Analytica | business, enterprise | London | 2014 |
| Cambridge University Press | book publisher, open-access publisher, university press, academic publisher | Cambridge | 1534 |
| Cannondale Bicycle Corporation | bicycle manufacturer, brand, business | Bethel | 1971 |
| Canoo | business, automobile manufacturer, public company | Torrance | 2017 |
| Cape Air | airline | Hyannis | 1989 |
| Capital One | business, enterprise, credit institution, public company | McLean | 1994 |
| Cardinal Health | business, medical device company, enterprise, public company | Dublin | 1971 |
| Carleton College | liberal arts college, private not-for-profit educational institution | Northfield | 1866 |
| 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 |
| Carrier Corporation | business, public company | Farmington | June 26, 1915 |
| Carroll Shelby International | automobile manufacturer | Enterprise | August 17, 1962 |
| Cartercar | business, automobile manufacturer | Pontiac | 1905 |
| Case Corporation | brand, business | United States | 1842 |
| Case IH | brand, business, tractor brand | Racine | 1984 |
| Castello di Amorosa | winery | — | April 2007 |
| Castle Rock Entertainment | television production company, film production company | Beverly Hills | June 19, 1985 |
| Caterpillar Inc. | business, enterprise, public company | Irving | 1925 |
| CBS | radio network, television network | CBS Building | September 18, 1927 |
| CBS Films | film production company, film distributor | Los Angeles | March 2007 |
| CBS Radio | business | New York City | 1928 |
| Cecil H. Green Library | academic library, library building | Stanford | 1919 |
| Celanese Corporation | business, public company | Irving | 1999 |
| Celera Corporation | business | Rockville, Alameda | May 1998 |
| Cell Press | imprint, academic publisher | Cambridge | 1986 |
| Centurion Air Cargo | airline | Miami International Airport | 1985 |
| Century 21 Real Estate | estate agent, business, enterprise | Madison | 1971 |
| Cerberus Capital Management | business, enterprise | New York City | 1992 |
| CH2M Hill | former entity, business | Meridian | 1946 |
| Champ Car | sports competition, recurring sporting event, business | — | 1979 |
| Chan Zuckerberg Initiative | limited liability company, organization, enterprise | Redwood City | 2015 |
| Chaosium | tabletop role-playing game publisher, board game publishing company, business | Hayward, Albany | October 31, 1975 |
| Chapman University | private not-for-profit educational institution, university | Orange | 1861 |
| Charlton Comics | business | Derby | 1945 |
| Charter Arms | business | Shelton | 1964 |
| Chateau Marmont | hotel | — | 1927 |
| Chautauqua Airlines | airline | Indianapolis | 1973 |
| Checker Motors Corporation | automobile manufacturer | Kalamazoo | 1922 |
| Chegg | dot-com company, technology company, public company | Santa Clara | 2005 |
| Chemical Bank | business | Midland, New York City | 1954 |
| Chevron Corporation | oil company, corporation, organization, gas station chain, enterprise, public company | — | — |
| Chicago Board of Trade | futures exchange, business | Chicago | 1848 |