| SIX Hills Investments Limited | Construction | 2017 |
| SIX Siblings Property Limited | Real estate | 2022 |
| Sizzlin RIG Limited | Hospitality | 2025 |
| SJ Hair Ltd | Other services | 2014 |
| SJ Sensory Ltd | Professional & scientific | 2026 |
| Sjapharm Ltd | Wholesale & retail | 2019 |
| SJH Direct Ltd | Professional & scientific | 2024 |
| SJH East Leake Ltd | Other services | 2024 |
| SJH Financial Services Ltd | Financial services | 2022 |
| SJH Oadby Ltd | Other services | 2024 |
| SJN Services Midlands Limited | Wholesale & retail | 2020 |
| SJR Inc Ltd | Construction | 2019 |
| SJT Solutions Limited | Professional & scientific | 2023 |
| SK & J Developments Limited | Construction | 2013 |
| SKA Leicester Limited | Hospitality | 2019 |
| Skandia Capital Markets Ltd | Financial services | 2025 |
| Sketch Evolution Ltd | Professional & scientific | 2011 |
| Sketchcad Limited | Extraterritorial | 2025 |
| Skezzas Shoe Cleaning Ltd | Administrative & support | 2025 |
| Skobex Construction Limited | Construction | 2025 |
| Sksh Limited | Health & social care | 2019 |
| SKV Business Partners Ltd | Administrative & support | 2021 |
| Skyblue Engineering Ltd | Professional & scientific | 2015 |
| Skydive Specialists Ltd | Manufacturing | 2017 |
| Skylarks Management Company Limited | Real estate | 2016 |
| Skyline Property Lets Ltd | Real estate | 2021 |
| Skylock Host Limited | Information & communication | 2008 |
| Skylock Limited | Information & communication | 2003 |
| Skyminers Limited | Administrative & support | 2014 |
| Skynet Ltd | Information & communication | 2002 |
| Slate and Scene Productions Limited | Information & communication | 2025 |
| Sleepunder Ltd | Other services | 2018 |
| Slgildoni Ltd | Health & social care | 2023 |
| Sliceup Pizza Ltd | Information & communication | 2024 |
| SLJ Scaffolding Ltd | Construction | 2022 |
| SLK Remedials Ltd | Construction | 2019 |
| Slnda Limited | Information & communication | 2018 |
| Slowlyf Limited | Arts & recreation | 2023 |
| SM Surgical Specialists Ltd | Health & social care | 2026 |
| SM U.K. Services Ltd | Construction | 2007 |
| SM1 Transport Ltd | Transport & logistics | 2025 |
| SM22 Transport Ltd | Transport & logistics | 2025 |
| Small BIZ Marketing Ltd | Professional & scientific | 2019 |
| Small Planet Live Limited | Administrative & support | 2014 |
| Smart Contact Ltd | Information & communication | 2018 |
| Smart Informatics and Multi-Hazard Reduction CIC | Professional & scientific | 2025 |
| Smart Logistics Consultancy Limited | Administrative & support | 2015 |
| Smart Phone Solutions Limited | Wholesale & retail | 2019 |
| Smart Surfacing Limited | Construction | 2013 |
| Smart Surveying Solutions Limited | Professional & scientific | 2016 |
| Smart Vision TV Limited | Wholesale & retail | 2014 |
| Smarterestates LLP | | 2018 |
| Smartfixx Ltd | Wholesale & retail | 2023 |
| Smarties Private Day Nursery Limited | Health & social care | 2006 |
| Smarttech Home Solutions Ltd | Construction | 2025 |
| Smarttlife Ltd | Wholesale & retail | 2023 |
| Smc.Property Services Ltd | Real estate | 2025 |
| SML Engineering Limited | Professional & scientific | 2023 |
| Smlab Ltd | Professional & scientific | 2026 |
| SMM Finance Limited | Professional & scientific | 2019 |
| Smooth Property Solutions Ltd | Real estate | 2018 |
| SMS Expert Ltd | Administrative & support | 2019 |
| Smti Ltd | Professional & scientific | 2024 |
| Smyth Fitness Limited | Arts & recreation | 2017 |
| SN Phillis Limited | Hospitality | 2018 |
| Snack World UK Limited | Wholesale & retail | 2018 |
| Snapsak Ltd | Wholesale & retail | 2026 |
| Snells Nook Residents Management Company Limited | Households | 2026 |
| Snflwr Ltd | Administrative & support | 2024 |
| Snowy (UK) Holdings Limited | Financial services | 2008 |
| SNR Parmar Holdings Ltd | Financial services | 2025 |
| SNR Property Ltd | Real estate | 2016 |
| Snrj Limited | Extraterritorial | 2023 |
| Snrk Property Limited | Real estate | 2016 |
| SNT Property Ltd | Real estate | 2022 |
| Snug Homeware Limited | Wholesale & retail | 2024 |
| Snus Global Ltd | Wholesale & retail | 2021 |
| Soar Consulting Governance and Leadership Solutions Ltd | Professional & scientific | 2025 |
| Soar Plant Group Ltd | Administrative & support | 2024 |
| Soar Valley (Homes) Limited | Construction | 1988 |
| Soar Valley Bar Supplies Ltd | Wholesale & retail | 2007 |
| Soar Valley Brides Limited | Wholesale & retail | 2017 |
| Soar Valley Consulting Ltd | Information & communication | 2018 |
| Soar Valley Dental Practice Limited | Health & social care | 2011 |
| Soar Valley Ducting Services Ltd | Construction | 2025 |
| Soar Valley Property Ltd | Real estate | 2020 |
| Soar Valley Services Limited | Professional & scientific | 2003 |
| Soasoft Ltd | Information & communication | 2009 |
| Socho Cricket AI Ltd | Manufacturing | 2025 |
| Social Hood Limited | Hospitality | 2022 |
| Socksmad Limited | Wholesale & retail | 2014 |
| Socon Pumps UK Limited | Manufacturing | 2014 |
| Sofa | Wholesale & retail | 1991 |
| Softwake Limited | Hospitality | 2026 |
| Software Sales Management Limited | Information & communication | 2013 |
| Sohum Capital Investments Ltd | Financial services | 2017 |
| SOL Homes Limited | Construction | 2007 |
| Soli Kitchen Limited | Hospitality | 2024 |
| Solumetrics Limited | Manufacturing | 1994 |
| Solumiq Ltd | Professional & scientific | 2026 |