| Sherwood Systems | Belfast |
| Shesh Tech | |
| SHF Web Solutions | |
| Shield Therapeutics plc | |
| Shieldplay | Greater London |
| Shields Environmental Group (Holdings) Ltd | Essex |
| Shift Bioscience Ltd | |
| Shift Bioscience Ltd | |
| Shift F7 Ltd | Surrey |
| Shift.ms | |
| SHINE Agency | |
| Shine Internet Ltd | |
| Shipamax Ltd | |
| ShipServ Ltd | |
| SHL | Surrey |
| Shook Digital | |
| Shop Circle | |
| Shopblocks | |
| Shopcreator | West Yorkshire |
| Shopit Ltd | |
| Shoppa | |
| Shopper.com | |
| Shoprocket Ltd | |
| ShopTill-e | |
| ShopTo | |
| Shopwave Ltd | |
| Shopwired | |
| Shore Communications Ltd | Greater London |
| ShortWave | Devon |
| Shout Digital | Tyne and Wear |
| Shout Platform Ltd | |
| Shout Telecoms | |
| Show+Tell | |
| ShowX Ltd | Greater London |
| Shrinext Ltd | |
| Shrink Studio Ltd | |
| Shropshire Web Design | Shropshire |
| Shufti Pro | |
| Si digital | |
| SIA Sheer | |
| SIBIT Ltd | |
| SICL Ltd | West Yorkshire |
| Sidekick Money Ltd | |
| Sidekick Studios London Ltd | |
| SideQuest | |
| Sien Web | |
| Sierra IT Training Services Ltd | Hampshire |
| Sift Ltd | Bristol |
| Sifted EU Ltd | Greater London |
| Siftware Ltd | Shropshire |