| Shepherd Cooper Limited | Wholesale & retail | 2020 |
| Sherwood Groundworks MK Ltd | Administrative & support | 2012 |
| Sheryne SR Ltd | Manufacturing | 2017 |
| Show Direct Limited | Arts & recreation | 2002 |
| Show Motion Trailers Ltd | Manufacturing | 2026 |
| Showfield Homes Limited | Real estate | 2014 |
| SHS Handling Solutions (Holdings) Ltd | Administrative & support | 2016 |
| SHS Handling Solutions Ltd | Manufacturing | 2016 |
| Siam Consulting Solutions Ltd | Professional & scientific | 2017 |
| Signature Events Hire Ltd | Administrative & support | 2024 |
| Signature Flowers (Bucks and Oxon) Ltd | Wholesale & retail | 2016 |
| Signature Maintenance 100 Ltd | Transport & logistics | 2020 |
| Siker Ltd | Information & communication | 2018 |
| Silvanito Holdings Limited | Financial services | 2021 |
| Silvanito Investments Limited | Financial services | 2023 |
| Silver Bridge Consulting Limited | Professional & scientific | 2009 |
| Silverbeet 2012 Limited | Construction | 2012 |
| Silverstone Classic and Race Cars Ltd | Wholesale & retail | 2015 |
| Silverstone Golf Club (2005) Limited | Arts & recreation | 2005 |
| Silvertide Limited | Agriculture & fishing | 1997 |
| Simco Homes (DE Stafford School) Limited | Real estate | 2019 |
| Simco Homes (EST 1961) Limited | Real estate | 2017 |
| Simco Homes Limited | Construction | 2013 |
| SIMIA786 Ltd | Professional & scientific | 2014 |
| Simon Watts Broadcasting Ltd | Information & communication | 2010 |
| Simply H&S Ltd | Public administration | 2018 |
| Simply Stories Ltd | Arts & recreation | 2025 |
| Simplyxdigital Ltd | Professional & scientific | 2018 |
| Simpson Accountants Limited | Professional & scientific | 2010 |
| Simran Bilkhu Limited | Health & social care | 2023 |
| Singlebuild Ltd | Construction | 2025 |
| Singsong Limited | Information & communication | 2002 |
| Sinum Group Ltd | Transport & logistics | 2025 |
| Sinumukr Ltd | Transport & logistics | 2023 |
| Sion Hall Family Office Ltd | Administrative & support | 2003 |
| Sipify Solutions Ltd | Information & communication | 2017 |
| Sirett Builders Limited | Administrative & support | 2011 |
| Sirius Clean Ltd | Administrative & support | 2024 |
| Site Tiling Solutions Limited | Construction | 2018 |
| Sitewide Drainage Services Ltd | Extraterritorial | 2024 |
| Sitewide Plant Hire Ltd | Administrative & support | 2013 |
| SIX Alpha Group Ltd | Manufacturing | 2026 |
| SJ Mobility Solutions Ltd | Wholesale & retail | 2021 |
| SJE Procurement Ltd | Extraterritorial | 2019 |
| SJH Property (MK) Limited | Real estate | 2010 |
| SJP Services (Hemel Hempstead) Limited | Administrative & support | 2015 |
| Sjsv Ltd | Administrative & support | 2012 |
| SK Oviya Express Ltd | Wholesale & retail | 2019 |
| Skill Diverse Ltd | Extraterritorial | 2023 |
| Skim Milk Supplies Limited | Wholesale & retail | 1961 |
| Skua Aviation Ltd | Wholesale & retail | 2023 |
| Sky High Courier Limited | Transport & logistics | 2022 |
| Skyline by Bivol Ltd | Construction | 2025 |
| Sleep United Ltd | Wholesale & retail | 2026 |
| Small Business Communications Limited | Information & communication | 1997 |
| Small Joinery Solutions Ltd | Construction | 2019 |
| Smart Autos (Banbury) Ltd | Wholesale & retail | 2015 |
| Smart AY Move Auctions Limited | Real estate | 2020 |
| Smart GAS Solutions Ltd | Construction | 2012 |
| Smart Investing Limited | Financial services | 2004 |
| Smart Move Auctions Ltd | Wholesale & retail | 2025 |
| Smart Office Services (UK) Limited | Administrative & support | 2007 |
| Smartfish Ltd | Professional & scientific | 2008 |
| Smarties Arts and Crafts Ltd | Arts & recreation | 2018 |
| Smartqbarrier Limited | Manufacturing | 2026 |
| Smashing Social Media Limited | Professional & scientific | 2021 |
| SMB (Buckingham) Limited | Professional & scientific | 2007 |
| Smith Bros Ltd | Real estate | 2024 |
| Smith Holloway Group Ltd | Wholesale & retail | 2023 |
| Smith Mcmanus Limited | Wholesale & retail | 2022 |
| SMR Corporate Services Limited | Professional & scientific | 1999 |
| Snypr Setting OUT Engineers Ltd | Construction | 2020 |
| Socage Access Systems Limited | Extraterritorial | 2025 |
| Softonets Limited | Information & communication | 2021 |
| Solaco Limited | Professional & scientific | 2002 |
| Solar on Demand Ltd | Construction | 2023 |
| Solarvision Service Company Limited | Other services | 2015 |
| Solomon Brooks UK Limited | Real estate | 2018 |
| Solorshipping Limited | Transport & logistics | 2012 |
| Solution Techniques Limited | Wholesale & retail | 1999 |
| Solutions Based Consulting Limited | Professional & scientific | 2015 |
| Somersby 15 Limited | Hospitality | 2024 |
| Somerset Advisory Limited | Professional & scientific | 2022 |
| Sophie Barlow Consulting Limited | Administrative & support | 2012 |
| Soundlings Ltd | Wholesale & retail | 2025 |
| Sounds-Write Limited | Education | 2003 |
| Sounds-Write Publishing Limited | Extraterritorial | 2005 |
| Southview I.T Services (Consultancy) Ltd | Information & communication | 2025 |
| SP Smart Security Ltd | Construction | 2021 |
| Spaniel Films Limited | Information & communication | 1999 |
| Spareryb Logistics Ltd | Transport & logistics | 2022 |
| Spinbio Limited | Professional & scientific | 2022 |
| Spinks Assets and Applications Ltd | Financial services | 2023 |
| Spinks Carpentry Ltd | Construction | 2010 |
| Splinters Carpentry Construction Ltd | Manufacturing | 2025 |
| Sportcor Holdings UK Limited | Information & communication | 2024 |
| Sports and Spaces Ltd | Professional & scientific | 2012 |
| Sportsbook Training Services Limited | Wholesale & retail | 2016 |
| Sportscars Direct Limited | Administrative & support | 2017 |
| SPR Carpentry Services Limited | Manufacturing | 2026 |