| Skin&Wellness Medics Ltd | Other services | 2025 |
| Skinside OUT UK Ltd | Other services | 2025 |
| Skiprope Ltd | Information & communication | 2019 |
| Skittercore Studios Limited | Information & communication | 2026 |
| Skop-Project Limited | Information & communication | 2025 |
| SKP Productions Ltd | Other services | 2024 |
| Sky Light Electrical Services Ltd | Energy | 2010 |
| SKY550 Limited | Transport & logistics | 2013 |
| Skyblue Planners Limited | Financial services | 2015 |
| Skyland Developments Ltd | Real estate | 2026 |
| Skylight Psychiatry Ltd | Health & social care | 2020 |
| Skyline Painting Services Ltd | Construction | 2022 |
| Skyrun Ltd | Wholesale & retail | 2025 |
| SL Delivers Ltd | Other services | 2025 |
| SL Transformation & Consulting Ltd | Professional & scientific | 2025 |
| SL Vehicle Solutions Limited | Wholesale & retail | 2016 |
| Slawek-Driver Ltd | Transport & logistics | 2019 |
| SLC Mulvey Ltd | Professional & scientific | 2015 |
| Slipstream Business Solutions Ltd | Professional & scientific | 2006 |
| SLR Environmental Ltd | Water & waste | 2010 |
| SLS Systems Limited | Information & communication | 2016 |
| Slv-Trans Limited | Transport & logistics | 2014 |
| SM Coaching LLP | | 2024 |
| SM Family Care Services Ltd | Administrative & support | 2025 |
| SM Plumbing Service Ltd. | Construction | 2016 |
| SM Skin Aesthetics Ltd | Other services | 2017 |
| SM Voice Advocacy Limited | Health & social care | 2015 |
| Smallwireless Limited | Professional & scientific | 2015 |
| Smart Bodyshop Limited | Wholesale & retail | 2012 |
| Smart Media Limited | Information & communication | 1995 |
| Smart Property Connections Ltd | Hospitality | 2026 |
| Smart Roofing Solutions Ltd | Construction | 2026 |
| Smart Spray Foam Removal Ltd | Administrative & support | 2025 |
| Smart Valet Ltd | Other services | 2021 |
| Smart-Paws Dog Grooming Ltd | Other services | 2018 |
| Smarter Connections Ltd | Professional & scientific | 2026 |
| Smarter Flow Limited | Information & communication | 2025 |
| Smarter Home Solutions Ltd | Construction | 2026 |
| Smartlet Property Ltd | Real estate | 2026 |
| Smartsaver Energy Ltd | Transport & logistics | 2025 |
| Smartstep UK Holdings Limited | Financial services | 2025 |
| Smartzone Intelligent Systems Ltd | Administrative & support | 2017 |
| SMB Group Limited | Professional & scientific | 2008 |
| Smcr Ltd | Construction | 2026 |
| Smeb Limited | Financial services | 2021 |
| Smeb PAY Limited | Administrative & support | 2023 |
| Smeb UK Holdings Limited | Information & communication | 2021 |
| Smiledent PVT Ltd | Health & social care | 2017 |
| Smiles Van Ltd | Hospitality | 2024 |
| Smilesnmore Digital Photography Ltd | Professional & scientific | 2025 |
| Smith Design & Detailing Ltd | Professional & scientific | 2026 |
| Smith Management & Consultancy Ltd | Professional & scientific | 2026 |
| Smithie (UK) Limited | Wholesale & retail | 2003 |
| Smithie IT Limited | Extraterritorial | 2016 |
| Smithie Lighting Limited | Extraterritorial | 2016 |
| Smugglers Bluff Limited | Hospitality | 2022 |
| SN Pharma Consulting Ltd | Wholesale & retail | 2026 |
| Snap Food and Wine Limited | Wholesale & retail | 2015 |
| Snap Marketing Ltd | Administrative & support | 2009 |
| Snezana Catering Limited | Hospitality | 2020 |
| SNG BDW (Kingston Bagpuize) LLP | | 2024 |
| SNG Community Foundation | Health & social care | 2024 |
| Snowflake Creative Limited | Information & communication | 2006 |
| Snowflake Design Limited | Information & communication | 2016 |
| SO Financial London Limited | Financial services | 2015 |
| Socca Chic Limited | Wholesale & retail | 2024 |
| Social Island Enterprise Ltd | Professional & scientific | 2023 |
| Sofi Designs Bridal Limited | Wholesale & retail | 2000 |
| Soft Ideas Limited | Information & communication | 2003 |
| Softfx Water Softeners Ltd | Wholesale & retail | 2021 |
| Sohan HP Ltd | Real estate | 2024 |
| Solara Ltd | Information & communication | 2018 |
| Sole Foot Health Ltd. | Administrative & support | 2019 |
| Solent 2009 Limited | Professional & scientific | 2009 |
| Solent Mediation Limited | Professional & scientific | 2001 |
| Solent Suites Ltd | Real estate | 2022 |
| Solicitude Training Limited | Health & social care | 2013 |
| Solid Rock Aviation LP | | 2020 |
| Solny Trans Ltd | Transport & logistics | 2024 |
| Solo MIA Ltd | Wholesale & retail | 2017 |
| Solomon Group Limited | Information & communication | 2003 |
| Solomon Technical Services Limited | Information & communication | 2002 |
| Solti Capital Limited | Financial services | 2017 |
| Solus Ipse Ltd | Information & communication | 2015 |
| Solutions for Information Assets Ltd | Information & communication | 2017 |
| Solutions Spring Ltd | Information & communication | 2007 |
| Solvd Ltd | Information & communication | 2008 |
| Solvexx Solutions Ltd | Other services | 2004 |
| Someaddress Networks Ltd | Information & communication | 2013 |
| Somerset Communications Ltd | Information & communication | 2017 |
| Somic Packaging UK Limited | Manufacturing | 2022 |
| Sommet Holdings Ltd | Real estate | 2024 |
| Sonsan Holdings Limited | Real estate | 2022 |
| Sophysical Physiotherapy and Sports Injury Clinic Ltd | Health & social care | 2016 |
| Soraya Express Ltd | Transport & logistics | 2025 |
| Soroptimist Exhibitions Limited | Administrative & support | 1998 |
| SOS GAS Plumbing & Heating Services Ltd | Construction | 2012 |
| SOS Smalley Limited | Administrative & support | 2009 |
| Soul Connect Properties Ltd | Real estate | 2024 |
| South Coast Cyber Solutions Limited | Information & communication | 2025 |