| Silverrock Solutions Limited | Information & communication | 2014 |
| Simms Care Services Limited | Health & social care | 2011 |
| Simply Successful Solutions Ltd | Administrative & support | 2008 |
| Singer Properties Ltd | Construction | 2025 |
| Singer Property Investments Ltd | Real estate | 2020 |
| Sinnesloschen Inc. Ltd | Information & communication | 2020 |
| Sip&Glow Ltd | Manufacturing | 2026 |
| Sixth Circle Tattoo and Piercing Lounge Ltd | Other services | 2022 |
| SJ Sourcing Group Ltd | Administrative & support | 2022 |
| SJ Sourcing Ltd | Administrative & support | 2018 |
| SJ Systems Ltd | Construction | 2014 |
| SJP Production Limited | Administrative & support | 2018 |
| Skillboost Solutions Limited | Public administration | 2025 |
| Sky Executive Homes Limited | Construction | 2025 |
| Sky Homes (LC) Limited | Construction | 2025 |
| SL HR Consulting Limited | Extraterritorial | 2020 |
| Slabs and Stones Limited | Manufacturing | 2011 |
| Sliq Cards Ltd | Wholesale & retail | 2025 |
| Sloansway Limited | Construction | 2009 |
| SM Builders & Electricians Ltd | Construction | 2024 |
| Small People Ltd | Health & social care | 2017 |
| Smart FK Construction Ltd | Construction | 2025 |
| Smart Formula Limited | Manufacturing | 2005 |
| Smart Location Ltd | Real estate | 2020 |
| Smart One Engineering Ltd | Construction | 2023 |
| SMART10 Limited | Administrative & support | 2012 |
| Smarter Homes Solutions Limited | Information & communication | 2019 |
| Smartflow Payments Limited | Financial services | 2017 |
| Smartier Group Holdings Ltd | Financial services | 2022 |
| Smartier Group Ltd | Construction | 2019 |
| Smartway Group Ltd | Administrative & support | 2021 |
| Smeco Ltd | Professional & scientific | 2025 |
| Smithfield Casings & Sundries Limited | Wholesale & retail | 1978 |
| Smooth Finishes Building Services Ltd | Construction | 2022 |
| Smvpharma Ltd | Transport & logistics | 2016 |
| Snacksol Ltd | Hospitality | 2022 |
| Snda Consultancy Ltd | Information & communication | 2019 |
| Soar Healthcare Limited | Health & social care | 2016 |
| Soar Industries Ltd | Construction | 2023 |
| Sodac Law UK Ltd | Transport & logistics | 2024 |
| Sofishop Ltd | Manufacturing | 2020 |
| Solange Hair and Beauty Limited | Other services | 2017 |
| Solarlux (UK) Limited | Professional & scientific | 2007 |
| Solarlux Systems Limited | Wholesale & retail | 1997 |
| Solrant Ltd | Wholesale & retail | 2024 |
| Solutions Defined Ltd | Professional & scientific | 2009 |
| Solvance Limited | Energy | 2025 |
| Solvex Trade Limited | Wholesale & retail | 2024 |
| Sotauro Ltd | Information & communication | 2018 |
| Soulette Ltd | Wholesale & retail | 2025 |
| Soundscape Sanctuary Ltd | Education | 2025 |
| Source and Supply Ltd | Wholesale & retail | 2009 |
| Southpaw Printing Limited | Manufacturing | 2017 |
| SP Supplies Ltd | Construction | 2022 |
| Spade Group Limited | Construction | 2015 |
| Spark Therapeutics UK Ltd | Health & social care | 2016 |
| Spear Electrical (London) Ltd | Construction | 2016 |
| Spectral MD UK Limited | Professional & scientific | 2021 |
| Spectrum Hair, Tanning & Beauty Salon Ltd | Other services | 2020 |
| Spen Hill Developments Limited | Administrative & support | 2003 |
| Spen Hill Management Limited | Construction | 1990 |
| Spen Hill Properties (Holdings) PLC | Construction | 1989 |
| Spen Hill Regeneration Limited | Construction | 2007 |
| Spen Hill Residential NO 1 Limited | Administrative & support | 2008 |
| Spen Hill Residential NO 2 Limited | Administrative & support | 2007 |
| SPH Carpentry & Construction Limited | Construction | 2020 |
| Spire Professional Services Limited | Information & communication | 2007 |
| Spoke Cycles CC Ltd | Wholesale & retail | 2017 |
| Spry Properties Limited | Real estate | 2021 |
| SRI Sairam Limited | Hospitality | 2013 |
| SRI Vasavi Homes Ltd | Financial services | 2022 |
| SRV Contractors Limited | Construction | 2024 |
| SS Brasserie Ltd | Hospitality | 2024 |
| ST Albans Mini Market Ltd | Wholesale & retail | 2026 |
| Stadia Consulting Group Ltd | Information & communication | 2020 |
| Stagg Drainage Limited | Extraterritorial | 2014 |
| Stanborough Construction Consultancy Services Limited | Professional & scientific | 2018 |
| Stanborough School | Education | 2012 |
| Stanford Thomas Ltd | Wholesale & retail | 2010 |
| Starform Engineering Limited | Professional & scientific | 2022 |
| STATS4BIOL Consultancy Limited | Professional & scientific | 2021 |
| Statusfloat Limited | Professional & scientific | 2003 |
| Stealthness Group Limited | Other services | 2023 |
| Stealthness Limited | Other services | 2023 |
| Steam Rescue Limited | Professional & scientific | 2023 |
| Stefan Lankov Limited | Construction | 2015 |
| Stella Care Solutions Limited | Administrative & support | 2021 |
| Stepping Stones Day Nursery (Totton) Limited | Health & social care | 2018 |
| Stepping-Stones Pre-School and Holiday Care C.I.C. | Health & social care | 2021 |
| Sterivida Pharma Limited | Manufacturing | 2025 |
| Sterling Court (WGC) Management Limited | Households | 2017 |
| Sterling IP Ltd | Professional & scientific | 2007 |
| Sterlingconsult Ltd | Professional & scientific | 2015 |
| Steven Gray Designs Limited | Professional & scientific | 2018 |
| Steven Setterfield Ltd | Construction | 2014 |
| Stockingwood Developments Limited | Real estate | 2024 |
| Stockingwood Financial Services Limited | Financial services | 2024 |
| Stokoe Design Services Limited | Professional & scientific | 2019 |
| Stol Ltd | Professional & scientific | 2025 |
| Stonehills Fish Bar Ltd | Hospitality | 2016 |