| Cyan Worlds | privately held company, video game developer, business | Wilmington, Mead | 1987 |
| Cygnus Solutions | business | — | November 13, 1989 |
| Cyrix | business, public company | Richardson | 1988 |
| Dag Hammarskjöld Library | library, library building | — | 1946 |
| Dallas Semiconductor | business | Dallas | February 1, 1984 |
| Danelectro | brand, business | Camarillo | 1947 |
| Danjaq | business, enterprise, company | Santa Monica | 1962 |
| Darden Restaurants | business, enterprise, public company | Orange County | 1968 |
| Datapoint | business | — | 1968 |
| Days of Wonder | board game publishing company | Paris | October 1, 2002 |
| Dayton Art Institute | nonprofit organization, arts educational institution, art museum | Dayton | 1930 |
| DC Studios | film production company | Burbank | November 1, 2022 |
| DC Universe | broadcaster, subscription, website, business, video streaming service, video on demand | Burbank | 2018 |
| Deck Nine | video game developer | Louisville | 1997 |
| Deckers Outdoor Corporation | business, enterprise, public company | Goleta | 1973 |
| Deep Space Industries | business, enterprise | Mountain View | January 22, 2013 |
| Defense Commissary Agency | supermarket chain, government agency | Fort Lee | October 1, 1991 |
| Defense Language Institute | military school, language school | — | 1954 |
| Del Monte Foods | business, enterprise | San Francisco | 1886 |
| Delaware State University | historically black college or university, public educational institution of the United States, university, land-grant university | — | 1891 |
| Dell EMC | business, enterprise, public company | Hopkinton | August 1979 |
| Dell Publishing | comics publishing company, publishing house | New York City | 1921 |
| Dell Technologies | business, enterprise, public company | Round Rock | September 7, 2016 |
| Delmonico's | restaurant | — | December 13, 1827 |
| DeLorean Motor Company | automobile manufacturer | Detroit | October 24, 1975 |
| Democratic National Committee | business | Washington, D.C. | 1848 |
| Denison University | liberal arts college, Colleges That Change Lives, private not-for-profit educational institution | — | 1831 |
| Denny's | restaurant chain, pancake house, public company | Spartanburg | 1953 |
| Desilu | television production company | Los Angeles | 1950 |
| Detroit Diesel | automobile manufacturer | Detroit | 1938 |
| DeVry University | private university | — | 1931 |
| Diamond Multimedia | business | Los Angeles | 1982 |
| DIC Entertainment Corporation | television production company, animation studio, film production company | Burbank | 1971 |
| Dickies | business, enterprise, brick and mortar | Fort Worth | 1918 |
| Dickinson College | college, private not-for-profit educational institution | Carlisle | 1783 |
| Diebold Nixdorf | business, enterprise, public company | North Canton | 1859 |
| DigiPen Institute of Technology | private for-profit educational institution, university | Redmond | 1988 |
| Digital Domain | public company | Playa Vista, Venice | 1993 |
| Digital Photography Review | website, business | — | 1998 |
| Digital Public Library of America | 501(c)(3) organization, digital library, website | Baldwin | 2010 |
| DigitalGlobe | business, defunct organization, enterprise | Westminster | 1992 |
| Diners Club International | business, enterprise | Riverwoods | 1950 |
| Discover Financial | commercial organization, credit institution, public company | Wilmington, Riverwoods | 1960 |
| Discovery, Inc. | business, enterprise, public company | New York City | 1982 |
| Dish | business, subsidiary company, enterprise | Meridian | 1996 |
| Disney Cruise Line | business, cruise line | Celebration | 1995 |
| Disney Music Group | record label, record company, business | Burbank | 1998 |
| Disney Television Animation | business | Glendale | December 5, 1984 |