| La MaMa Experimental Theatre Club | theatre company | — | 1961 |
| La Salle University | private not-for-profit educational institution, Catholic university | — | 1863 |
| La Senza | business, clothing store chain | Montreal | 1990 |
| La-Z-Boy | business, public company | Monroe | 1927 |
| Lafayette College | liberal arts college, private not-for-profit educational institution | Easton | 1826 |
| Landmark Worldwide | business, enterprise | San Francisco | 1991 |
| Langston University | historically black college or university, public educational institution of the United States, school, land-grant university, public university | — | 1897 |
| Lanteris Space Systems | privately held company, subsidiary company | Palo Alto | 1957 |
| Lantern Entertainment | film studio | Dallas | July 16, 2018 |
| LaSalle | automobile manufacturer | Detroit | 1927 |
| Latham & Watkins | organization, law firm | Los Angeles | 1934 |
| Laureate Education | international university, open-access publisher, education company, public company | Baltimore, Miami | 1998 |
| Lay’s | business | — | 1934 |
| LCG Entertainment, Inc. | video game publisher, video game developer | Malibu | December 27, 2018 |
| Leatherman | brand, business | Portland | 1983 |
| Lee | business, subsidiary company | Kansas, Merriam | 1889 |
| Legacy Fighting Alliance | business | Texas, United States | 2016 |
| Legendary Pictures | film production company | Burbank | 2000 |
| Legoland Florida | amusement park | — | October 15, 2011 |
| Lehman Brothers | investment bank, business, public company | New York City | 1850 |
| LenovoEMC | business, enterprise | San Diego | 1980 |
| Level 3 Communications | business, enterprise, public company | Frankfurt | 1985 |
| Levi Strauss & Co. | business, retail chain, enterprise, brick and mortar, public company | San Francisco, Levi's Plaza | 1853 |
| Lewis & Clark College | college, private not-for-profit educational institution | Portland | 1867 |
| Lexar | business | Milpitas | 1996 |
| Lexicon | business | Woodbury | 1971 |
| Liberty Media | business, public company | Douglas County, Colorado | 1991 |
| Library of America | nonprofit organization, publishing house, book series | New York City | 1979 |
| Lightstorm Entertainment | film production company | Santa Monica | 1990 |
| Lincoln Motor Company | car brand, automobile manufacturer, public company | Dearborn | 1917 |
| Lincoln University | historically black college or university, public educational institution of the United States, public university | — | 1854 |
| Linden Lab | business | San Francisco | 1999 |
| Ling-Temco-Vought | conglomerate | Cleveland | 1969 |
| Linguistic Society of America | nonprofit organization, open-access publisher, learned society | — | — |
| Linotype | type foundry, private press | Brooklyn, Bad Homburg vor der Höhe | 1895 |
| Lionbridge | business, enterprise, public company | Waltham | 1996 |
| Lionsgate Films | film production company | Santa Monica | 1998 |
| Lionsgate Television | television production company, business | North Vancouver | July 1997 |
| Litton Industries | business, enterprise | Milwaukee | 1953 |
| Live Nation Entertainment | record label, entertainment company, public company | Beverly Hills | 2005 |
| Loki Entertainment | video game developer | Tustin | November 9, 1998 |
| Lollapalooza | business, music festival | — | 1991 |
| Loma Linda University | church college, private not-for-profit educational institution, private university | Loma Linda | 1905 |
| Lonely Planet | travel website, book publisher, business | Melbourne | 1972 |
| Long Island Rail Road | commuter rail network, business, transport company | Jamaica | 1834 |
| Long-Term Capital Management | hedge fund firm, business, defunct organization | Greenwich | 1994 |
| Lorimar Television | television production company, film production company | Culver City | February 1, 1969 |
| Louisiana Tech University | public educational institution of the United States, university | — | 1894 |
| Love's Travel Stops & Country Stores | retail chain, gas station chain | Oklahoma City | 1964 |
| Lowe's | hardware store chain, public company | Mooresville | March 25, 1921 |
| Loyola Marymount University | Jesuit university, private not-for-profit educational institution, open-access publisher, private university | Los Angeles | 1865 |
| Loyola University Maryland | liberal arts college, private not-for-profit educational institution | — | 1852 |
| LSI Corporation | organization, business, public company | Milpitas | 1981 |
| LSU New Orleans | public educational institution of the United States, university | — | 1958 |
| Lubin Manufacturing Company | film production company | Philadelphia | 1902 |
| Lucas Entertainment | pornographic film distributor, pornography website, pornographic film studio | New York City | 1998 |
| Lunar and Planetary Laboratory | graduate school, research institute | — | 1960 |
| Lyric Opera of Chicago | nonprofit organization, opera company | Chicago | 1954 |
| Lytro | camera model, business | Mountain View | 2006 |