| Smart Custom Systems Ltd | Professional & scientific | 2014 |
| Smart ERP Solutions Ltd | Professional & scientific | 2010 |
| Smart Foot Care Limited | Health & social care | 2014 |
| Smart GL Logistics Ltd | Transport & logistics | 2024 |
| Smart Home Technologies Ltd | Manufacturing | 2024 |
| Smart Lighting Poland Limited | Construction | 2024 |
| Smart Snake Technology Limited | Information & communication | 2014 |
| Smartbooks Solutions Ltd | Professional & scientific | 2024 |
| Smarthaus Limited | Manufacturing | 2010 |
| Smarthouse & Partners Ltd | Construction | 2023 |
| Smash OUT Limited | Hospitality | 2025 |
| SMB Property & Building Solutions Limited | Real estate | 2025 |
| SMC Pipework Services Ltd | Construction | 2016 |
| SMG Renovations Limited | Construction | 2024 |
| Smile Day Centre Ltd | Health & social care | 2021 |
| Smile Trans Limited | Transport & logistics | 2018 |
| Smilee Associate Ltd | Wholesale & retail | 2025 |
| Smiling Land Ltd | Real estate | 2017 |
| Smith Accounting Limited | Professional & scientific | 2017 |
| Smith Contracting Limited | Professional & scientific | 2018 |
| Smith Designs Ltd | Professional & scientific | 2024 |
| Smith Square Advisory Ltd | Professional & scientific | 2025 |
| Smiths Fire Limited | Professional & scientific | 1998 |
| Smiths Fire LLP | | 2008 |
| SN Home Hero Ltd | Construction | 2025 |
| SN Securecorp Sales Limited | Administrative & support | 2004 |
| SNA Investment Holding UK Limited Partnership | | 2018 |
| Snap-On Finance UK Limited | Financial services | 1997 |
| Snap-On U.K. Holdings Limited | Manufacturing | 1991 |
| Snapdragon & BOP CIC | Other services | 2025 |
| Snapride Limited | Transport & logistics | 2023 |
| Snarling Beast Limited | Real estate | 2017 |
| Snowlynx Properties Ltd | Real estate | 2026 |
| Snubnose Ltd | Information & communication | 2026 |
| Soapure Ltd | Administrative & support | 2024 |
| Social Media Productions Ltd | Professional & scientific | 2021 |
| Sock-X Limited | Wholesale & retail | 2025 |
| Sohal Estates Limited | Real estate | 2018 |
| Sohan's Aulakh Properties Ltd | Real estate | 2021 |
| Soho Developments Ltd | Real estate | 2024 |
| Solace Contribution CIC | Other services | 2020 |
| Solar Express Ltd | Transport & logistics | 2020 |
| SOLAR4ALL Ltd | Construction | 2025 |
| Solara Shades UK Limited | Manufacturing | 2025 |
| Sole and Sound Clinic Ltd | Health & social care | 2024 |
| Solent Scale Holdings Ltd | Financial services | 2011 |
| Solent Scale Services Limited | Manufacturing | 2000 |
| Solicitude Ltd. | Construction | 2013 |
| Solier Energy Management Ltd | Information & communication | 2025 |
| Solihull Care Services Limited | Health & social care | 2022 |
| Soller Holdings Limited | Real estate | 2017 |
| Sollertia Technology Ltd | Information & communication | 2025 |
| Solmazten Hairdressers Limited | Other services | 2018 |
| Solution Angel Limited | Wholesale & retail | 2013 |
| Solution Housing Limited | Real estate | 2022 |
| Solutions at Studio 59 Limited | Wholesale & retail | 2020 |
| Solutions Strategy Research Facilitation Limited | Professional & scientific | 2001 |
| Solvesmart Legal Limited | Professional & scientific | 2021 |
| Som&Gi Limited | Real estate | 2023 |
| Somal (UK) Limited | Real estate | 2006 |
| Somerport Limited | Administrative & support | 2010 |
| Something Borrowed Ltd | Administrative & support | 2021 |
| Sonder & Sage Ltd | Other services | 2025 |
| Sonez Ltd | Manufacturing | 2023 |
| Sonido Sessions Ltd | Arts & recreation | 2026 |
| Sonnenblume Holdings Ltd | Financial services | 2026 |
| Sonny Developments Limited | Professional & scientific | 2013 |
| Soothing Sleep Ltd | Information & communication | 2024 |
| SOP Solutions Ltd | Transport & logistics | 2023 |
| Soporific Limited | Wholesale & retail | 2018 |
| Sora Luxe Ltd | Administrative & support | 2025 |
| Sorcha Abrams Limited | Professional & scientific | 2023 |
| Sorrel 009 Limited | Extraterritorial | 1944 |
| Soul CUT Films Ltd | Information & communication | 2023 |
| Soul in Cyan Limited | Arts & recreation | 2025 |
| Soundhaus Properties Limited | Financial services | 2017 |
| Sounds Good Audio Ltd | Information & communication | 2022 |
| Souschef ML Ltd | Information & communication | 2025 |
| South West Forklifts Limited | Construction | 2014 |
| Southern Mart Limited | Wholesale & retail | 2020 |
| Southfield Black Country Limited | Financial services | 2021 |
| Sovereign House Investment Properties Limited | Real estate | 2021 |
| Space Solution Interiors Limited | Construction | 2016 |
| Spaghetti Rock Ltd | Hospitality | 2019 |
| Spanger Chops Ltd | Financial services | 2020 |
| Sparkle Kettering Ltd | Administrative & support | 2025 |
| Sparrow Care and Support Ltd | Health & social care | 2019 |
| Sparrow Construction Ltd | Construction | 2017 |
| Sparrow Craft Ltd | Wholesale & retail | 2023 |
| Spartan Rescue Limited | Administrative & support | 1998 |
| Spearca Electrical Services Ltd | Construction | 2026 |
| Spearhead Turf Limited | Agriculture & fishing | 1986 |
| Specialist Marine Fasteners Limited | Wholesale & retail | 2019 |
| Specialist Remediation Solutions Ltd | Water & waste | 2023 |
| Spectral Windows Limited | Manufacturing | 2020 |
| Speed Light Delivery Ltd | Transport & logistics | 2026 |
| SPEEDTWIN49 Ltd | Real estate | 2023 |
| Spendloves Trading Limited | Administrative & support | 2026 |
| Spire Air Conditioning Limited | Construction | 2025 |
| Splendiferous Aesthetics Ltd | Health & social care | 2024 |