| U.S. Cellular | business, enterprise, public company | Chicago | 1983 |
| Uber | food delivery, platform company, Internet booking engine, ridesharing company, organization, business, data controller, online taxi service, enterprise, software, public company | San Francisco | March 2009 |
| Ubiquiti | business, enterprise, public company | New York City | October 2003 |
| Udemy | website, education company | San Francisco | 2010 |
| UL LLC | standards organization, certification services provider, partnership | Northbrook | 1894 |
| Ulta Beauty | business, retail chain, public company | Bolingbrook | 1990 |
| Ultimate Pro Wrestling | business | California | 1998 |
| Undead Labs | business | Seattle | November 23, 2009 |
| Under Armour | business, enterprise, public company | Baltimore | 1996 |
| Unimation | business | — | 1962 |
| Union College | private not-for-profit educational institution, private university | Schenectady | February 25, 1795 |
| Union Iron Works | business | San Francisco | 1849 |
| United Airlines | holding company, airline, public company | Chicago, Willis Tower | April 6, 1926 |
| United Airlines Holdings | business, enterprise, public company | Chicago | December 30, 1968 |
| United Express | brand, airline | Chicago | 1985 |
| United Launch Alliance | launch service provider, privately held company | Centennial | December 1, 2006 |
| United Natural Foods | business, public company | Providence | 1996 |
| United Plankton Pictures | privately held company | Burbank | April 1, 1998 |
| United Space Alliance | business, enterprise | Houston | August 1995 |
| United States Army Command and General Staff College | staff college | Fort Leavenworth | 1881 |
| United States Army Infantry School | military infantry school | Fort Benning | 1918 |
| 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 Military Academy | Direct Reporting Unit, public educational institution of the United States, military museum, military academy | — | March 16, 1802 |
| United States National Library of Medicine | national library, medical library | Bethesda | 1836 |
| United States Navy Strike Fighter Tactics Instructor program | military school | — | March 3, 1969 |
| United States Playing Card Company | publishing house, business | Erlanger | 1867 |
| United States Rubber Company | business | Naugatuck | 1892 |
| United States Wrestling Association | business | Memphis | 1989 |
| United Technologies Corporation | business, enterprise, public company | Hartford | 1929 |
| Universal Animation Studios | television production company, animation studio | Universal City, Glendale | 1991 |
| Universal Content Productions | television production company | Universal City | June 1, 2008 |
| Universal Studios Home Entertainment | media distributor | Universal City | 1979 |
| University of Alabama at Birmingham | public educational institution of the United States, public research university | — | 1969 |
| University of Alabama in Huntsville | public educational institution of the United States, university | — | 1950 |
| University of Alaska System | state university system | Fairbanks | 1917 |
| University of Arkansas for Medical Sciences | medical university, public educational institution of the United States | — | 1879 |
| 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, Irvine | public educational institution of the United States, public research university | — | 1965 |
| 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, San Diego | public educational institution of the United States, public university | — | November 18, 1960 |
| University of Central Arkansas | public educational institution of the United States, university | — | 1907 |
| University of Central Missouri | public educational institution of the United States, university | — | 1871 |
| University of Charleston | private not-for-profit educational institution, private university | — | 1888 |
| University of Chicago Law School | law school | Chicago | 1902 |
| University of Chicago Press | book publisher, university press | Chicago | 1891 |
| University of Cincinnati | public educational institution of the United States, public research university | — | 1819 |
| University of Dayton | private not-for-profit educational institution, university | — | 1850 |
| University of Denver | research university, private not-for-profit educational institution, private university | Denver | 1864 |
| University of Dubuque | private not-for-profit educational institution, school, university | — | 1852 |
| University of Georgia | university | Old North Campus | 1785 |
| University of Guam | university, land-grant university | — | 1952 |
| University of Hawaii Press | open-access publisher, university press | Honolulu | 1947 |
| University of Hawaiʻi at Mānoa | public educational institution of the United States, land-grant university, public university | — | 1907 |
| University of Illinois Chicago | public educational institution of the United States, open-access publisher, public university | — | January 1983 |
| University of Illinois Springfield | public educational institution of the United States, university | — | 1969 |
| University of Iowa | public educational institution of the United States, public research university | Iowa City | 1847 |
| 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 Maine | public educational institution of the United States, land-grant university, public research university | — | 1865 |
| University of Maryland | publishing house, public educational institution of the United States, land-grant university, public research university | College Park | 1856 |
| 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 Miami | private not-for-profit educational institution, university | Coral Gables | 1925 |
| University of Michigan Law School | law school | — | 1859 |
| University of Michigan Press | open-access publisher, university press | Ann Arbor | 1930 |
| University of Michigan–Flint | public educational institution of the United States, university | — | 1956 |
| University of Minnesota | production company, public educational institution of the United States, open-access publisher, land-grant university, public research university | Minneapolis | 1851 |
| University of Missouri–Kansas City | public educational institution of the United States, public university | — | 1933 |
| University of Nebraska Omaha | public educational institution of the United States, public university | — | 1908 |
| University of Nevada, Las Vegas | public educational institution of the United States, public research university | Las Vegas | September 10, 1957 |
| University of Nevada, Reno | public educational institution of the United States, land-grant university, public research university | Reno | 1874 |
| University of North Carolina at Asheville | liberal arts college, public educational institution of the United States | Asheville | 1927 |
| 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 Carolina Wilmington | public educational institution of the United States, public university | Wilmington | 1947 |
| University of North Florida | public educational institution of the United States, university | — | 1969 |
| 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 Oregon | research university, public educational institution of the United States, public university | Eugene | 1876 |
| University of Phoenix | private for-profit educational institution, university | Phoenix | 1976 |
| 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 Rhode Island | research university, public educational institution of the United States, open-access publisher, land-grant university, public university | Kingston | 1892 |
| 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 San Francisco | publishing house, private not-for-profit educational institution, university, open-access publisher | San Francisco | 1855 |
| University of South Carolina | research university, public educational institution of the United States, public university | — | 1801 |
| 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 Tennessee at Chattanooga | public educational institution of the United States, public university | — | 1886 |
| University of Texas at Arlington | public educational institution of the United States, public research university | Arlington | 1895 |
| University of Texas at Dallas | public educational institution of the United States, university | — | 1961 |
| University of Texas at El Paso | public educational institution of the United States, public research university | El Paso | 1914 |
| University of Texas at San Antonio | public educational institution of the United States, university | — | 1969 |
| University of Texas Press | university press | Austin | 1950 |
| University of Texas Southwestern Medical Center | public educational institution of the United States, medical organization, medical school | — | 1943 |
| University of Texas System | state university system | Austin | 1876 |
| University of the Incarnate Word | private not-for-profit educational institution, university | — | 1881 |
| University of the Virgin Islands | historically black college or university, land-grant university, public university | — | March 16, 1962 |
| University of Utah | public educational institution of the United States, public research university | — | 1850 |
| 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 West Georgia | public educational institution of the United States, university | — | 1906 |
| University of Wisconsin System | state university system | Madison | 1848 |
| University of Wisconsin–Madison | public educational institution of the United States, land-grant university, public research university | — | 1848 |
| University of Wisconsin–Stevens Point | public educational institution of the United States, university, public university | Stevens Point | 1894 |
| University System of Maryland | state university system | Baltimore | 1988 |
| UPS Airlines | cargo airline | Louisville | 1988 |
| USRobotics | business, enterprise | Schaumburg | 1976 |