| Softvize Premier Ltd | Information & communication | 2025 |
| Software Hunter Ltd | Information & communication | 2019 |
| Software Leaders Limited | Information & communication | 2002 |
| Software Solutions International Limited | Extraterritorial | 1993 |
| Soha Sultan International Ltd | Wholesale & retail | 2025 |
| Sohanrsps Ltd | Information & communication | 2019 |
| Sohopoms Limited | Wholesale & retail | 2022 |
| SOL Financial Ltd | Professional & scientific | 2025 |
| SOL Property Group Ltd | Real estate | 2026 |
| SOL Property Management Ltd | Real estate | 2018 |
| Solablack Ltd | Other services | 2025 |
| Solace Group Holdings Ltd | Real estate | 2020 |
| Solace Recordings Limited | Information & communication | 2026 |
| Solace Studio Ltd | Other services | 2025 |
| Solana IQ Ltd | Information & communication | 2026 |
| Solar Bird Proofing Ltd | Administrative & support | 2024 |
| Solar Green Limited | Professional & scientific | 2001 |
| Solar PV Ltd | Construction | 2021 |
| Solar Wise Roofing and Building Services Ltd | Construction | 2020 |
| Solarithm Ltd | Energy | 2025 |
| Sole Bay Trading Ltd | Information & communication | 2012 |
| Solmia LLP | | 2007 |
| Solo Property & Developments Ltd | Construction | 2020 |
| Solo Scaffolding (Holdings) Limited | Administrative & support | 2017 |
| Solomon Building Ltd | Construction | 2016 |
| Soltech Electrical Ltd | Construction | 2024 |
| Soltris Limited | Administrative & support | 2025 |
| Solus (Colchester) Management Company Limited | Households | 2005 |
| Solus Four (Colchester) Management Company Limited | Households | 2007 |
| Solus Plumbing & Heating Limited | Construction | 2021 |
| Solus Three (Colchester) Management Company Limited | Households | 2007 |
| Solus Two (Colchester) Management Company Limited | Households | 2006 |
| Solutioneering Ltd | Information & communication | 2006 |
| Solve System Solutions Limited | Information & communication | 2014 |
| Solve With Software Limited | Information & communication | 2012 |
| Solvertrex Limited | Professional & scientific | 2015 |
| Soma Group Ltd | Manufacturing | 2019 |
| Somasutra Limited | Health & social care | 2022 |
| Some Label Ltd | Other services | 2024 |
| Sommly Ltd | Information & communication | 2026 |
| Sona Insurance Solutions Ltd | Financial services | 2019 |
| Sonali Colchester Limited | Hospitality | 2025 |
| Sonali Takeway Ltd | Hospitality | 2018 |
| Sonic Boom Productions Limited | Arts & recreation | 2005 |
| Sonic Butterfly Limited | Hospitality | 2026 |
| Sonnie Electrical Ltd | Construction | 2015 |
| Sons Way Limited | Other services | 2017 |
| Soom Media Company Ltd | Professional & scientific | 2025 |
| Soontex Textile Supply Office Ltd | Wholesale & retail | 2024 |
| Sophie CN Limited | Administrative & support | 2021 |
| Sophie Tilks Ltd | Professional & scientific | 2024 |
| Sophie's Nails & Beauty Ltd | Other services | 2023 |
| Sophie's Swim School Ltd | Arts & recreation | 2024 |
| Sophies Place Beauty Ltd | Other services | 2025 |
| Sophisticut Limited | Other services | 2003 |
| Sorelle Properties Limited | Real estate | 2005 |
| Soris Acquisition Ltd | Financial services | 2021 |
| Soris Capital Partners Limited | Financial services | 2019 |
| SOS Carpentry & Bespoke Joinery Ltd | Manufacturing | 2021 |
| SOS Electrical Limited | Construction | 2024 |
| SOS Scaffolding Wivenhoe Limited | Construction | 2012 |
| SOS Solutions Limited | Construction | 2011 |
| SOS Teams Ltd | Information & communication | 2026 |
| Soto Realty Ltd | Real estate | 2025 |
| Sound Factory Ltd | Manufacturing | 2015 |
| Sounddataos Limited | Information & communication | 2025 |
| South Central Residents Limited | Households | 2002 |
| South East Ceilings & Interiors Limited | Construction | 2017 |
| South East Developments Ltd | Construction | 2010 |
| South East Employment Solutions Limited | Administrative & support | 2009 |
| South London Nursing Homes Limited | Health & social care | 1981 |
| South Norfolk Carers Limited | Health & social care | 2002 |
| South Street Romford (Block E) Management Company Limited | Real estate | 1989 |
| Southborough Ltd | Real estate | 2010 |
| Southcliff Hall R.T.M. Company Limited | Households | 2009 |
| Southcliffe Trailer Company Limited | Hospitality | 1949 |
| Southeast Asbestos Limited | Construction | 2019 |
| Southeast Carpenters Ltd | Manufacturing | 2024 |
| Southern Family Care Ltd | Health & social care | 2012 |
| Southern Safety Consultancy Ltd | Professional & scientific | 2025 |
| Southey & Co Limited | Real estate | 2022 |
| Southgate Agriculture Limited | Agriculture & fishing | 2020 |
| Southgate Builders Ltd | Construction | 2025 |
| Southlings Limited | Real estate | 2021 |
| Southsurv Ltd | Professional & scientific | 2025 |
| Southview Tiling Limited | Construction | 2012 |
| Southway House Limited | Real estate | 2010 |
| Sovereign Crescent Management Limited | Other services | 1998 |
| Sovik Ltd | Wholesale & retail | 2024 |
| Soyeiya Colchester Ltd | Other services | 2023 |
| SP Homes & Development Ltd | Real estate | 2021 |
| SP Pipeline & Sewers Ltd | Construction | 2022 |
| SP Plumbing & Bathrooms Ltd | Construction | 2021 |
| SP Roofcraft Ltd | Construction | 2025 |
| SP Store Ltd | Wholesale & retail | 2021 |
| SP Tippers Limited | Administrative & support | 2012 |
| Spa GH 4 Limited | Real estate | 2025 |
| Spa Students 1 Limited | Real estate | 2024 |
| Spa Students 2 Limited | Real estate | 2024 |
| Spa Students 3 Limited | Real estate | 2024 |