| Sharptel Limited | Information & communication | 2015 |
| Shears UK Ltd | Administrative & support | 2007 |
| Sheepish Ltd | Wholesale & retail | 2019 |
| Shelley Court Maintenance Company Limited | Households | 1966 |
| Sherbourne Court Freehold Ltd | Real estate | 2023 |
| Sheridan Games Ltd | Wholesale & retail | 2021 |
| Sherlock Fmcg Consulting Ltd | Professional & scientific | 2026 |
| Sherriff Court Managements Limited | Households | 1987 |
| Shezzo's Ltd | Hospitality | 2019 |
| Shibusa Limited | Information & communication | 2014 |
| Shifter Technology Ltd | Professional & scientific | 2025 |
| Shiloh Lodges Ltd | Other services | 2024 |
| Shineup Ltd | Administrative & support | 2025 |
| Shire Electrical Services Limited | Construction | 2015 |
| Shoreline Press (UK) Ltd | Construction | 2012 |
| Shot in the ARM (Herts) Limited | Professional & scientific | 2023 |
| Sice Trading Limited | Construction | 2021 |
| Sifaa Ltd | Health & social care | 2022 |
| Silchenko Ltd | Information & communication | 2022 |
| Silox UK Ltd | Wholesale & retail | 2003 |
| Silver Fern IT Services Ltd. | Information & communication | 1999 |
| Silver London Limited | Extraterritorial | 2008 |
| Simon Foster Consulting Limited | Professional & scientific | 2016 |
| Simpsons Inventories Limited | Households | 2025 |
| Simsof Limited | Professional & scientific | 2015 |
| Sirgan Financial and Business Solutions Limited | Professional & scientific | 2009 |
| Site Circle Ltd | Information & communication | 2015 |
| Sitecircle Smart Tech Ltd | Information & communication | 2024 |
| Sitges Capital Ltd | Financial services | 2019 |
| SJD Legal Services Limited | Professional & scientific | 2007 |
| SJG Consultancy Ltd | Professional & scientific | 2015 |
| SJK Maternity Services Ltd | Health & social care | 2022 |
| Skawa Construction Services Limited | Construction | 2009 |
| Skhills for Life Ltd | Education | 2025 |
| SKI MUM Limited | Real estate | 2020 |
| SKJ Legal Limited | Extraterritorial | 2013 |
| Sknk Sknk Ltd | Information & communication | 2023 |
| Skuggi U.K. Ltd | Health & social care | 2021 |
| Skye 2024 Ltd | Professional & scientific | 2024 |
| Slight Edge Europe Limited | Other services | 2017 |
| Slotema Strategic Risk Consultancy Ltd | Financial services | 2025 |
| SM House Trading Ltd | Real estate | 2025 |
| Smart Fit Furniture Ltd | Manufacturing | 2016 |
| Smart-Watt Ltd | Construction | 2024 |
| Smartdirect Consultant Limited | Professional & scientific | 2021 |
| Smartr Innovations Limited | Information & communication | 2018 |
| Smith & Gosnold Limited | Information & communication | 2008 |
| Smith's Field Limited | Real estate | 2012 |
| Smithwell Consulting Limited | Professional & scientific | 2014 |
| Smpg Holdings Ltd | Real estate | 2026 |
| Snagmanager Limited | Information & communication | 2003 |
| Snail Objects Ltd | Manufacturing | 2025 |
| Snug Events Ltd | Professional & scientific | 2014 |
| SO Boxing Ltd | Other services | 2024 |
| Sociable Limited | Professional & scientific | 2009 |
| Socialstar Technology Ltd | Information & communication | 2023 |
| Socoa Limited | Wholesale & retail | 2017 |
| Sofina Active Ltd | Wholesale & retail | 2021 |
| Soilex Environmental Ltd | Professional & scientific | 2019 |
| Soilex Logistics Ltd | Transport & logistics | 2021 |
| Soilex Regeneration Limited | Water & waste | 2025 |
| Sokostena Ltd | Administrative & support | 2021 |
| Solace Finance Ltd | Financial services | 2022 |
| Solar 45 LDA Limited | Financial services | 2025 |
| Solar AM Ltd | Manufacturing | 2026 |
| Solarc Ltd | Information & communication | 2012 |
| Solargreen Digital Ventures Limited | Financial services | 2025 |
| Solid Vision Limited | Manufacturing | 1982 |
| Solo Lettings Ltd | Real estate | 2019 |
| Sonder International Limited | Administrative & support | 2021 |
| Songs for Children Limited | Information & communication | 1986 |
| Songs for Christmas Limited | Information & communication | 1994 |
| Sonoran Consultancy Limited | Professional & scientific | 2008 |
| SOO Design and Architectural Consultants Ltd | Wholesale & retail | 2021 |
| Sorrento Management (Llandrindod Wells) Limited | Households | 2014 |
| Sorwe Ltd | Information & communication | 2019 |
| Sotogen Ltd | Real estate | 2025 |
| Soup London Tour Operator Ltd | Information & communication | 2011 |
| Source Support Limited | Administrative & support | 2008 |
| Sourced by AY Limited | Other services | 2024 |
| South London Movers Ltd | Transport & logistics | 2017 |
| Southdown Associates Limited | Information & communication | 2014 |
| Southdown Barber Ltd | Other services | 2012 |
| Southdown Coffee Shop Ltd | Hospitality | 2019 |
| Southdown Partybox Ltd | Wholesale & retail | 2021 |
| Southdown Property Development Ltd | Real estate | 2013 |
| Southdown Property Investment Ltd | Real estate | 2019 |
| Southdown Property Limited | Real estate | 2013 |
| Southdown Property Management Limited | Households | 2017 |
| Southdown Spice Ltd | Hospitality | 2019 |
| Southgate Court Residents Association Limited | Households | 1995 |
| Sovereign BUS Ltd | Transport & logistics | 2026 |
| SP & JD Property Investments Ltd | Real estate | 2017 |
| Space Lettings Limited | Real estate | 2010 |
| Spacechips Ltd | Professional & scientific | 2014 |
| Spanish Properties Assets Management Ltd | Real estate | 2003 |
| Spark Therapy Limited | Health & social care | 2023 |
| Sparks Wiseman and Rafe Ltd | Information & communication | 2024 |
| Spcl Limited | Hospitality | 2009 |
| Specialist Recording Company Ltd | Information & communication | 2001 |