| Skype Communications S.à r.l. | Luxembourg |
| Smart Oversight | Esch-sur-Alzette |
| Smart Oversight | Esch-sur-Alzette |
| SMBC Nikko Bank (Luxembourg) S.A. | |
| SnapSwap International S.A. | Luxembourg |
| Softbrik | |
| Softkis Luxembourg | Mersch |
| Sogel Luxembourg | Capellen |
| Sogeti Luxembourg | Luxembourg |
| Solutions S.A. | Luxembourg |
| Solutions30 | Luxembourg |
| SonyCenter Luxembourg | Luxembourg |
| Space Hack Luxembourg | |
| space4environments S.à.r.l. | |
| Spacety Luxembourg S.A. | |
| SPARC Industries S.à.r.l. | |
| Spiece S.A. | Esch-sur-Alzette |
| Startup Luxembourg | Esch-sur-Alzette |
| Startup Wold Cup Challenge | |
| Stellar Récupération de Données Luxembourg | Luxembourg |
| Stéphanie Walter | |
| STOKR | |
| Supercomputing Luxembourg | |
| SustainCERT | |
| SWiRL S.A. | |
| Sword Group | Capellen |
| syn2cat | |
| Tadaweb | Esch-sur-Alzette |
| Tadaweb S.A. | |
| Talarian S.à r.l. | |
| Taler Systems S.A. | |
| Talkii by Sovi | |
| Talkwalker | Luxembourg |
| Tango | |
| Tech Family Ventures | |
| Technology Partner S.à r.l. | |
| Technoport S.A. | Esch-sur-Alzette |
| Technoport S.A. | |
| Telindus | Luxembourg |
| Telkea ICT S.A. | Luxembourg |
| TenTwentyFour S.à.r.l. | Capellen |
| Tetrao | |
| Tetris Communication | |
| The IT Department.net | Esch-sur-Alzette |
| The Lordz Games Studio | Luxembourg |
| The Network | |
| The Office Luxembourg | |
| The Recruiter S.à r.l. | |
| TheMarketsTrust | Luxembourg |
| ThreeFold S.A. | |