| Name | Region |
|---|---|
| Tele2 Eesti AS | Harju |
| Telegrupp AS | Tartu |
| Televõrgu AS | Harju |
| TeleX AI | |
| Telia Eesti AS | Harju |
| Tera Ventures | Harju |
| Terabill OÜ | Harju |
| Texen | |
| The Better Bunch OÜ | |
| Thermony | |
| Thorgate | |
| Tiger Softwares | |
| Timbeter | |
| TK8 Software | Tartu |
| Toggl | |
| Toggl OÜ | Harju |
| Top Connect | Harju |
| Topconf | Harju |
| Touchlane OÜ | |
| TravelLine | |
| Traxby OÜ | |
| Trenet AS | Harju |
| Trind Ventures | Harju |
| Trinidad Wiseman OÜ | |
| TTÜ Küberneetika Instituut | Harju |
| TurboDoc | |
| Turnit | |
| Turundus OÜ | Tartu |
| Tuum | |
| TVG Eesti OÜ | Harju |
| U.niTalk OÜ | |
| UCS Estonia OÜ | Harju |
| ULANDERS OÜ | |
| Ulge Design | Harju |
| Ultima Design OÜ | Harju |
| Ultra Corporation OÜ | |
| Umesh Space OÜ | |
| Undetect OÜ | |
| UniBee | |
| Union FinTech | |
| Uniraja Ltd | Harju |
| United Angels VC | Harju |
| United Skills | |
| University of Tartu Startup Lab | |
| Univoice OÜ | Harju |
| Unschooler OÜ | |
| UpSteam Eesti OÜ | |
| Upstreem.com OÜ | |
| Uptime | Harju |
| Urest OÜ |