| Soletrend Apparel Ltd | Wholesale & retail | 2025 |
| Solid P&M Ltd | Transport & logistics | 2025 |
| Solstice Advanced Materials UK Limited | Administrative & support | 2024 |
| Somerville Gardens Residents Company Ltd | Real estate | 2024 |
| Something Marvellous Limited | Extraterritorial | 2011 |
| Soni and Associates Ltd | Professional & scientific | 2018 |
| Soni Assets Limited | Real estate | 2023 |
| Soni Performance Limited | Professional & scientific | 2020 |
| Sonik Solutions Limited | Professional & scientific | 2015 |
| Sonn Investments Ltd | Real estate | 2024 |
| Sophie Hadley Ltd | Wholesale & retail | 2021 |
| Sophie Marie Limited | Professional & scientific | 1995 |
| Soteria Planning Limited | Administrative & support | 2017 |
| Sound Wave Media Limited | Administrative & support | 2017 |
| Soundtrack of Your Life Limited | Information & communication | 2024 |
| South East Formwork Limited | Construction | 2020 |
| South East Labels Limited | Manufacturing | 2002 |
| South East Transport Consultants Ltd | Professional & scientific | 2020 |
| Southern Ductwork (Manufacture) Ltd | Manufacturing | 1999 |
| Southern Equine Sheath Cleaning Limited | Administrative & support | 2018 |
| Southern Property Care Limited | Construction | 2015 |
| SP & MR Property Ltd | Real estate | 2012 |
| SP Assessments (South) Limited | Financial services | 2022 |
| Spa Creators Ltd | Professional & scientific | 2012 |
| Spade and Archer Limited | Professional & scientific | 2006 |
| Spareslot Ltd | Information & communication | 2025 |
| Sparkle Boutique Ltd | Health & social care | 2026 |
| Sparrow Wing Care Limited | Health & social care | 2024 |
| Sparta Systems (UK) Limited | Information & communication | 2014 |
| Spartan Roofing Ltd | Construction | 2023 |
| Spashell Limited | Other services | 2016 |
| Special Branch 24/7 Ltd | Administrative & support | 2014 |
| Specialised Paintwork Limited | Extraterritorial | 1999 |
| Specialist Care Providers Ltd | Health & social care | 2026 |
| Spectacular Events Limited | Hospitality | 2023 |
| Spectra Logic Europe Limited | Wholesale & retail | 2000 |
| Spencer Industries Ltd | Information & communication | 2020 |
| Spencer Jones Limited | Information & communication | 2025 |
| Spice & Ice Limited | Hospitality | 2015 |
| Spice N Saver Ltd | Wholesale & retail | 2025 |
| Spicers Domestic Services Limited | Administrative & support | 2010 |
| Spin Trading Limited | Wholesale & retail | 2001 |
| Spinners Chester Limited | Arts & recreation | 2022 |
| Spinners Northampton Limited | Arts & recreation | 2022 |
| Spinners Plymouth Limited | Hospitality | 2022 |
| Spinners Reading Limited | Arts & recreation | 2019 |
| Spinners Solihull Limited | Hospitality | 2022 |
| Spiral Creative Limited | Administrative & support | 2008 |
| Spiro Fitting Services Ltd | Construction | 2016 |
| Split Trading Ltd | Financial services | 2000 |
| Sploj Limited | Arts & recreation | 2019 |
| Spoilt Collection Limited | Wholesale & retail | 2015 |
| Spoilt UK Limited | Wholesale & retail | 2015 |
| Spoken Brand Narratives Limited | Professional & scientific | 2014 |
| Sportex Global Ltd | Arts & recreation | 2020 |
| Sporting Solutions (MGA) Limited | Manufacturing | 2020 |
| Sports and Orthopaedic Physiotherapy Limited | Health & social care | 2012 |
| Spot Gym Buddy Ltd | Arts & recreation | 2024 |
| Spot-On Control Cables Limited | Manufacturing | 1987 |
| Springwood Group Ltd | Construction | 2019 |
| Spud Wagon Reading Limited | Hospitality | 2025 |
| Spyderbyte Tech Ltd | Information & communication | 2025 |
| Squadra Carrozzeria Ltd | Wholesale & retail | 2018 |
| Square Mile Consultancy Services Limited | Professional & scientific | 2025 |
| Squeaky Clean Pros Limited | Administrative & support | 2025 |
| Squishy Consultation Ltd | Real estate | 2024 |
| Squishy Services Ltd | Administrative & support | 2020 |
| SR Made to Shine Ltd | Administrative & support | 2026 |
| SRI Venkateshwara (Balaji) Temple & Cultural Centre | Other services | 2018 |
| SRL Interiors Limited | Construction | 2017 |
| SRT Construction Limited | Construction | 2013 |
| SS Investment Holding Ltd | Financial services | 2019 |
| SSB Travel Limited | Administrative & support | 2020 |
| Ssecureit Ltd | Information & communication | 2025 |
| Ssmanha Ltd | Information & communication | 2026 |
| SSR Consultancy Services Ltd | Professional & scientific | 2023 |
| SSR Property Investments Ltd | Real estate | 2017 |
| ST John Fabrications Ltd | Manufacturing | 2012 |
| ST Philips International Ltd | Professional & scientific | 2019 |
| ST3PIT Ltd | Construction | 2016 |
| Staiko Limited | Administrative & support | 2000 |
| Stamford Security Services Ltd. | Administrative & support | 2011 |
| Stamm Investments Limited | Construction | 1959 |
| Stan the Handyman Limited | Construction | 2018 |
| Standard Railway Wagon Company Limited(The) | Energy | 1933 |
| Stanley Electric (U.K.) Company Limited | Wholesale & retail | 2000 |
| Stanley Electric Holding Europe Co., Limited | Administrative & support | 2006 |
| Stapearl Limited | Hospitality | 2025 |
| Star UK Bidco Limited | Financial services | 2019 |
| Star UK Holdco Limited | Financial services | 2019 |
| Star UK Midco Limited | Financial services | 2019 |
| Star UK Topco Limited | Financial services | 2020 |
| Starkxen Limited | Information & communication | 2019 |
| Stars Rise Ltd | Health & social care | 2023 |
| Stasoon Ltd | Construction | 2016 |
| Static Brighton Limited | Manufacturing | 2022 |
| Statik UK Limited | Other services | 2007 |
| Stay Windsor Ltd | Hospitality | 2026 |
| Steadman James Ltd | Financial services | 2018 |
| Steel Construction Institute(The) | Professional & scientific | 1985 |