| SRO Solutions Ltd | Greater Manchester |
| Ssdc Ltd | Hampshire |
| SSERC Ltd | |
| SSHTOOLS Ltd | Cornwall |
| SSL247 | |
| SSP Ltd | West Yorkshire |
| St Clements Services Ltd | Northamptonshire |
| St Cross Electronics | |
| ST Electronics Ltd | Berkshire |
| St George's, University of London | |
| St John's College - Computer Science & Joint Schools | Oxfordshire |
| St Mary's University | |
| St Mary's University College Belfast | |
| St Patrick's College | Greater London |
| St. John's Innovation Centre | Cambridgeshire |
| Stability AI Ltd | |
| StableMate Systems Ltd | |
| Stacker Software Ltd | |
| Stacksoft | |
| StackStudio.digital Ltd | Greater London |
| StackZone Ltd | |
| Staff Absence Management Ltd | |
| Stafford Web | Staffordshire |
| Stafford Web Studio | |
| Staffordshire University | Staffordshire |
| Staffordshire University - School of Digital, Technologies and Arts | Staffordshire |
| Stainless Games Ltd | Isle of Wight |
| Stak | Warwickshire |
| Stampede | Edinburgh |
| Stand Out Property Manager | Lancashire |
| Standard Chartered Bank | Greater London |
| STANLEY Security | Wiltshire |
| Star Computer Services (UK) Ltd | Warwickshire |
| Star Digital Marketing Services Ltd | Buckinghamshire |
| Star Micronics EMEA Ltd | Buckinghamshire |
| Star Web Innovations | Berkshire |
| Starbit Ltd | |
| Stargazer Digital | |
| Stark | Surrey |
| Starling Bank | Greater London |
| Starlite Software | Staffordshire |
| Starsol Ltd | Norfolk |
| Start Me Up | |
| Start With Data | |
| Startadesign Ltd | Hertfordshire |
| Starthawk | |
| StarTraq Ltd | Oxfordshire |
| Startup Direct | Tyne and Wear |
| Startup Events List | |
| Startup Giants plc | |