| Thirdstrand | California |
| Thirdweb | California |
| Thirstie | |
| Thirty Seven Media and Marketing Group | |
| This Week in Startups | California |
| thismoment | California |
| ThisWay Global | Texas |
| THLG Media | Missouri |
| THM Solutions, LLC | Ohio |
| Thobson Technologies | |
| Thom Infotech | Illinois |
| Thom Little Associates Ltd | New Hampshire |
| Thoma Bravo, LLC | California |
| Thomas Aquinas College | California |
| Thomas Bolton Network Services | California |
| Thomas College | Maine |
| Thomas Computing Services | Florida |
| Thomas Edison State University | New Jersey |
| Thomas Electronics, Inc. | Illinois |
| Thomas Fuchs | New York |
| Thomas Imaginative, LLC | |
| Thomas Jefferson University | Pennsylvania |
| Thomas More College of Liberal Arts | New Hampshire |
| Thomas More University | Kentucky |
| Thomas Technologies Ltd | Texas |
| Thomas Technologies, Inc. | Illinois |
| Thomas University | Georgia |
| Thomas Wong | |
| Thomason Technologies, LLC | |
| Thompson Capital Partners | Arizona |
| Thompson Retractor | Michigan |
| Thompson Retractor | |
| Thompson Software Solutions, Inc. | Georgia |
| Thompson Surgical Instruments, Inc. | Michigan |
| Thomson Data, LLC | Texas |
| Thomson Reuters | |
| Thomvest Venture Capital | California |
| Thomvest Ventures | |
| Thor Solutions | |
| Thorburn Associates | California |
| Thorlabs, Inc. | New Jersey |
| Thornsoft Development, Inc. | New York |
| Thoroughbred Software International, Inc. | New Jersey |
| ThorpeForms.com | Florida |
| Thought Mechanics, LLC | Colorado |
| Thought Streams, Inc. | Georgia |
| Thought, Inc. | California |
| thoughtbot, Inc. | Texas |
| Thoughtcast Media | |
| ThoughtData, Inc. | Massachusetts |