| Syhtek Software Solutions | |
| Sylvera Ltd | |
| Symatrix Ltd | Greater Manchester |
| SymbaSync Ltd | |
| Symbe | |
| Symbiant | West Yorkshire |
| Symbios Group | Hampshire |
| Symbiosis Pharmaceutical Services | |
| Symfonie Capital | Greater London |
| Symmetrical | |
| Symmetry Investments | |
| Symogen | |
| SymphoMe | |
| Symphony | South Yorkshire |
| Symphony Ltd | Wiltshire |
| Symstar IT | Greater London |
| SymTerra | |
| Syn-Star PC Store | Hampshire |
| Synairgen plc | |
| Synamedia | |
| Synap Learning Ltd | West Yorkshire |
| Synapse Network | |
| Synaptec Ltd | Glasgow |
| SynaptixBio Ltd | |
| Synapx Ltd | |
| Synaxis Data Services Ltd | Greater Manchester |
| Synbiosis | |
| Synchtank | |
| Syncline | Greater London |
| SyncTecho | |
| Syndeo Ltd | |
| Syndicate Room Ltd | |
| Syndico Distribution Ltd | |
| Synectic Design Ltd | Greater Manchester |
| Synectics Solutions Ltd | Staffordshire |
| Syner-Med (Pharmaceutical Products) Ltd | |
| Synergist | Cheshire |
| Synergy Agency Ltd | |
| Synergy Technology Ltd | Lancashire |
| SynergyGroup | Hertfordshire |
| Synetec | |
| Synetica Ltd | |
| Synetics plc | South Yorkshire |
| Synetiq Ltd | |
| Syngene | |
| SynGenSys Ltd | |
| Syngis Software Development | |
| Synima | |
| Synk Ltd | Berkshire |
| Synmek Ltd | |