| Gab | dot-com company, social networking service, online community | Austin | August 15, 2016 |
| Gale | publishing house | Detroit, Farmington Hills | 1954 |
| Gallaudet University | private not-for-profit educational institution, university | Washington, D.C. | 1857 |
| GameStop | business, retail chain, enterprise, brick and mortar, public company | Grapevine | August 20, 1980 |
| Gathering of Developers | video game publisher, business | Texas | January 1998 |
| Gatorade | drink brand, trademark, business | Chicago | 1965 |
| Gearbox Software | video game publisher, video game developer | Frisco | January 1999 |
| General American Transportation Corporation | business, enterprise, public company | Chicago | 1933 |
| General Atomics Aeronautical Systems | subsidiary company, enterprise | Poway | 1993 |
| General Dynamics | business, public company | Reston | February 21, 1952 |
| Genesys | business, enterprise | Daly City | 1990 |
| Gensler | architectural firm, business | San Francisco | 1965 |
| Genzyme | business, subsidiary company, enterprise | Cambridge | 1981 |
| Geological Society of America | nonprofit organization, publishing house, open-access publisher, learned society | Boulder | 1888 |
| George Bush Presidential Library | museum, library | — | 1997 |
| George Mason University | public educational institution of the United States, university | Fairfax County | 1957 |
| George Washington University | research university, private not-for-profit educational institution, open-access publisher, private university | — | 1821 |
| Georgia Southern University | public educational institution of the United States, university, open-access publisher | — | 1906 |
| Georgia Southern University-Armstrong Campus | public educational institution of the United States, university | — | 1935 |
| Georgia Tech | university of technology, public educational institution of the United States, public research university | Atlanta | October 13, 1885 |
| Georgia-Pacific | privately held company, business, enterprise, public company | Atlanta, Georgia-Pacific Tower | 1927 |
| Gerber Legendary Blades | organization, business | Tigard | 1939 |
| Gerber Products Company | business, subsidiary company | Fremont | 1927 |
| Getty Images | joint-stock company, photo archive, photo agency, public company | Seattle | 1995 |
| Getty Oil | business, gas station chain | East Meadow | 1964 |
| Giant Sparrow | video game developer, business, enterprise | Santa Monica | March 22, 2009 |
| Gibson Brands | business, musical instrument manufacturing company | Tennessee, Nashville | 1902 |
| Gideons International | book publisher, religious organization, nonprofit organization, organization | Nashville | July 1, 1899 |
| GitHub | crowdsourced project, repository hosting service, repository web interface, issue tracking system, service on Internet, code reviewing software, continuous integration software, technology company, web application, forge, social networking service, website+4 | San Francisco | October 19, 2007 |
| Global Infrastructure Partners | investment fund, business | New York City | May 2006 |
| Global Payments | business, public company | Atlanta | 2000 |
| GlobalFoundries | business, enterprise, public company | Malta | October 7, 2008 |
| Globalstar | telecommunications company | Covington | 1998 |
| Gloria Jean's Coffees | business, café chain | Castle Hill | 1979 |
| Glu Mobile | video game publisher, video game developer, business, enterprise, public company | San Francisco | 2005 |
| GNC | business, enterprise, public company | Pittsburgh | 1935 |
| Godiva Chocolatier | chocolaterie | New York City | 1926 |
| GoJet Airlines LLC | airline | Bridgeton | 2004 |
| Gonzaga University | Jesuit university, private not-for-profit educational institution | Spokane | 1887 |
| Google | technology company, online service, business, identity provider, public company | Mountain View, Googleplex | September 4, 1998 |
| Google Fiber | network service provider | — | February 10, 2010 |
| Goose Island Brewery | brewery | Chicago | 1988 |
| GoPro | trademark, business, public company | San Mateo | 2002 |
| GoTo | software company, enterprise, public company | Boston | 2003 |
| Governors State University | public educational institution of the United States, university | — | 1969 |
| Gracie Films | television production company, film production company | Culver City | 1987 |
| Graflex | business | Rochester | 1889 |
| Graham-Paige | business, automobile manufacturer | Evansville | 1927 |
| Grambling State University | historically black college or university, public educational institution of the United States, university | Grambling | 1901 |
| Gramercy Pictures | film production company, film distributor | Universal City, Los Angeles | 2015 |
| Grauman's Chinese Theatre | movie theater | — | May 18, 1927 |
| Greenwood Publishing Group | book publisher | Santa Barbara | 1967 |
| Grinnell College | liberal arts college, private not-for-profit educational institution, school, organization | — | 1846 |
| Griptonite Games | video game developer | Kirkland | 1994 |
| Grubhub | food delivery, online service, business, subsidiary company, enterprise | Chicago | 2004 |
| GTE | business, enterprise | Stamford | 1918 |
| Guardian Industries | business | Auburn Hills | 1932 |
| Gulf and Western Industries | conglomerate | New York City | 1934 |