| U-Haul | car rental company, business, public company | Phoenix | 1945 |
| U.S. Bancorp | business, financial institution, credit institution, public company | Minneapolis | 1850 |
| U.S. Cellular | business, enterprise, public company | Chicago | 1983 |
| U.S. Steel | business, enterprise, public company | Pittsburgh | 2001 |
| Ubiquiti | business, enterprise, public company | New York City | October 2003 |
| UGG | business | Goleta | 1978 |
| UiPath | company, public company | New York City | 2005 |
| Ulta Beauty | business, retail chain, public company | Bolingbrook | 1990 |
| Ultimate Fighting Championship | mixed martial arts organization, enterprise | Nevada, Las Vegas | 1993 |
| Union Carbide | business, enterprise | Danbury | 1957 |
| Union Iron Works | business | San Francisco | 1849 |
| Union Pacific Railroad | railway company, public company | Omaha | 1862 |
| United Airlines | holding company, airline, public company | Chicago, Willis Tower | April 6, 1926 |
| United Artists | film production company, company | Culver City | February 5, 1919 |
| United Express | brand, airline | Chicago | 1985 |
| United Launch Alliance | launch service provider, privately held company | Centennial | December 1, 2006 |
| United Press International | news agency, organization, business, enterprise | Washington, D.C. | 1907 |
| United Space Alliance | business, enterprise | Houston | August 1995 |
| United States Army Command and General Staff College | staff college | Fort Leavenworth | 1881 |
| United States Army War College | Direct Reporting Unit, staff college, military school | — | 1901 |
| United States Centers for Disease Control and Prevention | United States federal agency, open-access publisher | Atlanta | — |
| United States Coast Guard Academy | military school, public educational institution of the United States, coast guard academy, military academy | New London | 1876 |
| United States Government Publishing Office | legislative branch agency, state publisher | — | 1861 |
| United States Information Agency | defunct government institution, civil service, information ministry, independent agency of the United States government, photo agency | Washington, D.C. | August 1953 |
| United States Merchant Marine Academy | naval academy, public educational institution of the United States | — | 1943 |
| United States Military Academy | Direct Reporting Unit, public educational institution of the United States, military museum, military academy | — | March 16, 1802 |
| United States Playing Card Company | publishing house, business | Erlanger | 1867 |
| United States Rubber Company | business | Naugatuck | 1892 |
| United States Wrestling Association | business | Memphis | 1989 |
| Universal Pictures | film production company, film studio | Universal City | April 30, 1912 |
| Universal Studios Hollywood | theme park | — | 1964 |
| University of Alabama | public educational institution of the United States, public university | Tuscaloosa | 1831 |
| University of Alabama in Huntsville | public educational institution of the United States, university | — | 1950 |
| University of Alaska Southeast | public educational institution of the United States, university | — | 1972 |
| University of Alaska System | state university system | Fairbanks | 1917 |
| University of Arkansas | public educational institution of the United States, land-grant university, public research university | Fayetteville | 1871 |
| University of Austin | private not-for-profit educational institution, university | — | — |
| University of California | state university system, land-grant university | Oakland | 1868 |
| University of California College of the Law, San Francisco | law school, public educational institution of the United States, university, academic publisher | — | 1878 |
| University of California, Berkeley | United Nations Depository Library, public educational institution of the United States, land-grant university, public research university | Berkeley | March 23, 1868 |
| University of California, Berkeley School of Law | law school | — | 1894 |
| University of California, Los Angeles | public educational institution of the United States, public research university | Los Angeles | May 23, 1919 |
| University of California, Merced | public educational institution of the United States, doctoral university: higher research activity, university, census-designated place in the United States | — | 2002 |
| University of California, Santa Cruz | educational institution, university | — | 1965 |
| University of Central Arkansas | public educational institution of the United States, university | — | 1907 |
| University of Chicago Law School | law school | Chicago | 1902 |
| University of Chicago Press | book publisher, university press | Chicago | 1891 |
| University of Colorado Boulder | research university, public educational institution of the United States, public university | — | 1876 |
| University of Colorado Denver | public educational institution of the United States, public university | — | 1912 |
| University of Dayton | private not-for-profit educational institution, university | — | 1850 |
| University of Delaware | public educational institution of the United States, land-grant university, public university | Newark | 1743 |
| University of Denver | research university, private not-for-profit educational institution, private university | Denver | 1864 |
| University of Evansville | private not-for-profit educational institution | Evansville | 1854 |
| University of Guam | university, land-grant university | — | 1952 |
| University of Hawaii Press | open-access publisher, university press | Honolulu | 1947 |
| University of Hawaiʻi–West Oʻahu | public educational institution of the United States, university | Kapolei | 1976 |
| University of Illinois Springfield | public educational institution of the United States, university | — | 1969 |
| University of Kansas | publishing house, public educational institution of the United States, university, open-access publisher, public research university | — | March 21, 1864 |
| University of Kentucky | public educational institution of the United States, open-access publisher, land-grant university, public university | Lexington | 1865 |
| University of Louisiana at Lafayette | public educational institution of the United States, university | Lafayette | 1900 |
| University of Louisville | public educational institution of the United States, public research university | Louisville | 1798 |
| University of Massachusetts | state university system | Boston | 1863 |
| University of Massachusetts Boston | public educational institution of the United States, university | Dorchester | 1964 |
| University of Massachusetts Lowell | public educational institution of the United States, public university | Lowell | 1975 |
| University of Memphis | public educational institution of the United States, public research university | — | 1912 |
| University of Michigan–Flint | public educational institution of the United States, university | — | 1956 |
| University of Minnesota Duluth | public educational institution of the United States, public university | — | 1895 |
| University of Missouri–Kansas City | public educational institution of the United States, public university | — | 1933 |
| University of Montana | research university, public educational institution of the United States, public university | — | 1893 |
| University of Nebraska Omaha | public educational institution of the United States, public university | — | 1908 |
| University of North Alabama | public educational institution of the United States, public university | — | 1830 |
| University of North Carolina at Asheville | liberal arts college, public educational institution of the United States | Asheville | 1927 |
| University of North Carolina at Chapel Hill | public educational institution of the United States, public research university | — | December 11, 1789 |
| University of North Carolina at Charlotte | public educational institution of the United States, public research university | — | 1946 |
| University of North Carolina at Greensboro | public educational institution of the United States, university, open-access publisher | Greensboro | 1891 |
| University of North Carolina Press | nonprofit organization, open-access publisher, university press | Chapel Hill | 1922 |
| University of North Texas | public educational institution of the United States, public research university | Denton | 1890 |
| University of Notre Dame | private not-for-profit educational institution, open-access publisher, Catholic university, private university, academic publisher | — | November 26, 1842 |
| University of Oklahoma | public educational institution of the United States, university, public research university | Norman | 1890 |
| University of Oklahoma Press | university press | Norman | — |
| University of Portland | private not-for-profit educational institution, Catholic university | — | 1901 |
| University of Puerto Rico | public university | — | 1903 |
| University of Puget Sound | liberal arts college, Colleges That Change Lives, private not-for-profit educational institution | Tacoma | 1888 |
| University of Richmond | private not-for-profit educational institution, university | Richmond | 1830 |
| University of Rochester | private not-for-profit educational institution, university | Rochester | 1850 |
| University of Saint Joseph | private not-for-profit educational institution, university | — | 1932 |
| University of San Diego | private not-for-profit educational institution, private university | San Diego | 1949 |
| University of South Florida | public educational institution of the United States, open-access publisher, public university | — | 1956 |
| University of Southern Mississippi | public educational institution of the United States, open-access publisher, public university | — | March 30, 1910 |
| University of St. Thomas | private not-for-profit educational institution, private university | Saint Paul | 1885 |
| University of Tampa | private not-for-profit educational institution, university | — | 1931 |
| University of Tennessee | neighborhood, research university, public educational institution of the United States, university, land-grant university, sun grant institution, public university | Knoxville | 1794 |
| University of Texas at El Paso | public educational institution of the United States, public research university | El Paso | 1914 |
| University of Texas Southwestern Medical Center | public educational institution of the United States, medical organization, medical school | — | 1943 |
| University of the People | nonprofit organization, community organization, private university | — | 2009 |
| University of the Virgin Islands | historically black college or university, land-grant university, public university | — | March 16, 1962 |
| University of Toledo | public educational institution of the United States, public research university | — | 1872 |
| University of Vermont | public educational institution of the United States, open-access publisher, land-grant university, public research university | Burlington | 1791 |
| University of Virginia School of Law | law school, faculty | — | 1819 |
| University of Wisconsin Press | university press | Madison | 1936 |
| University of Wisconsin System | state university system | Madison | 1848 |
| University of Wisconsin–La Crosse | public educational institution of the United States, public university | — | 1909 |
| University of Wisconsin–Madison | public educational institution of the United States, land-grant university, public research university | — | 1848 |
| University of Wisconsin–Milwaukee | research university, public educational institution of the United States, public university | Milwaukee | 1885 |
| University of Wyoming | public educational institution of the United States, land-grant university, public university | — | March 1886 |
| University System of Maryland | state university system | Baltimore | 1988 |
| UPA | film production company | Burbank | 1944 |
| Upjohn | pharmaceutical company, business, company | Michigan, Kalamazoo | 1886 |
| Upwork | organization, business, freelance marketplace, enterprise, public company | Palo Alto | 2015 |
| URS Corporation | business, enterprise | Transamerica Pyramid, San Francisco | 1951 |
| US Airways | airline | Tempe | 1937 |
| US Airways Express | airline | Tempe | 1967 |
| US Foods | business, public company | Rosemont | August 1, 1989 |
| USAA | insurance company, bank, business, financial institution | — | 1922 |
| Ushahidi Inc. | nonprofit organization, technology company | Nairobi | January 9, 2008 |
| UUNET | business | Ashburn | 1987 |