| Sirane International Ltd | Manufacturing | 2016 |
| Siri Lettings Ltd | Real estate | 2020 |
| Sirius Contracts (UK) Ltd | Construction | 2013 |
| Sirius Electrical Limited | Construction | 2003 |
| Sirmad Ltd | Health & social care | 2022 |
| Sirva Invest Ltd | Construction | 2016 |
| Sisbro Investments Ltd | Real estate | 2021 |
| Siso Consultancy Ltd | Health & social care | 2023 |
| Site Data (Sutton Coldfield) Limited | Professional & scientific | 1986 |
| SITE360 Ltd | Information & communication | 2022 |
| SIX 2 SIX Homes Limited | Construction | 2022 |
| SIX Flags Ltd | Hospitality | 2020 |
| Sixsigma Management Limited | Professional & scientific | 2014 |
| Sixty Three Russell Terrace Management (Leamington Spa) Limited | Households | 1974 |
| SJ Human Resources Consulting Ltd | Professional & scientific | 2019 |
| SJ Morgan Holdings Limited | Real estate | 2019 |
| SJ Ripley Properties Limited | Real estate | 2025 |
| SJA Property Investments Limited | Real estate | 2020 |
| Sjbl Nuttall FIC Limited | Financial services | 2024 |
| SJC Engineering Solutions Ltd | Wholesale & retail | 2023 |
| SJF Electrical & Building Services Ltd | Construction | 2011 |
| SJGHB13 Limited | Real estate | 2024 |
| Sjjs Management Limited | Real estate | 2022 |
| SJM Engineering Solutions Limited | Professional & scientific | 2018 |
| SJP Education Consulting Ltd | Real estate | 2023 |
| SJR Consulting Group Limited | Professional & scientific | 2024 |
| SJR Maintenance Ltd | Construction | 2025 |
| SK Haulage & Logistics Ltd | Transport & logistics | 2022 |
| SK Management Services Ltd | Education | 2025 |
| SK Powell Properties Ltd | Real estate | 2021 |
| SK8 House Limited | Arts & recreation | 2009 |
| SKB Incorporation Limited | Real estate | 2025 |
| SKC Recruitment Ltd | Administrative & support | 2020 |
| SKG Management Services Limited | Households | 2022 |
| SKG Midlands Ltd | Professional & scientific | 2023 |
| Skillcraft Products Ltd | Manufacturing | 2017 |
| Skilldiligence Ltd | Information & communication | 2026 |
| SKILLS4SUCCESS UK Limited | Professional & scientific | 2008 |
| Skin Surgery Clinic Tunbridge Wells Ltd | Health & social care | 2026 |
| Skinfluence Limited | Wholesale & retail | 2021 |
| SKN Locum Ltd | Real estate | 2014 |
| SKS Empire UK Ltd | Wholesale & retail | 2022 |
| SKS Sustainable Ltd | Wholesale & retail | 2023 |
| Sky Investors NUL Ltd | Hospitality | 2018 |
| Skybeck Ltd | Wholesale & retail | 2011 |
| Skyfare Travel Limited | Administrative & support | 1985 |
| Skylark Labs Ltd | Information & communication | 2023 |
| Skyline Banners Limited | Professional & scientific | 2013 |
| Skyline Roofing Contractors 2023 Limited | Construction | 2023 |
| Skywater Limited | Hospitality | 2024 |
| SL Properties Francis RD Ltd | Real estate | 2014 |
| SL Risk Management Consultancy Limited | Professional & scientific | 2023 |
| Slade Heath Barns (NO. 1) Management Limited | Households | 2008 |
| Slan GRC Services Ltd | Information & communication | 2026 |
| Slater Jetting Ltd | Professional & scientific | 2019 |
| Slater Samuels Properties Limited | Administrative & support | 2010 |
| Slaters Collectibles Ltd Ltd | Wholesale & retail | 2026 |
| SLG Investments 2017 Limited | Financial services | 2017 |
| Slick N Shine Limited | Wholesale & retail | 2022 |
| SLM Outsourcing Limited | Administrative & support | 2026 |
| SLP Investment & Management Ltd | Financial services | 2025 |
| SM Collective Agencies Ltd | Arts & recreation | 2024 |
| SM Fashion Trends Limited | Wholesale & retail | 2019 |
| SM Harris Enterprises Ltd | Hospitality | 2025 |
| SM Mods Limited | Wholesale & retail | 2019 |
| SM Traders & Wholesaler Limited | Wholesale & retail | 2015 |
| Smacleish Engineering Ltd | Wholesale & retail | 2016 |
| Small Concepts Ltd | Other services | 2022 |
| Smansion Homes Limited | Real estate | 2020 |
| Smart AI Consulting Limited | Information & communication | 2026 |
| Smart Boiler Company Midlands Ltd | Construction | 2020 |
| Smart Developments (Central) Limited | Extraterritorial | 2005 |
| Smart Developments (Midlands) Limited | Construction | 1999 |
| Smart Developments London Limited | Construction | 2010 |
| Smart Factory Solutions Ltd | Professional & scientific | 2018 |
| Smart Homes Sheepy Ltd | Real estate | 2026 |
| Smart Interiors and Design Ltd | Other services | 2024 |
| Smart Moves Financial Services Limited | Financial services | 2007 |
| Smart Party Marquees Ltd | Administrative & support | 2016 |
| Smart Solutions (Midlands) Ltd | Construction | 2024 |
| Smart Sparkz Ltd | Construction | 2014 |
| Smart Start Childcare (N) Ltd | Health & social care | 2026 |
| Smart Start Holdings Ltd | Financial services | 2025 |
| Smart Start Nursery Trading AS Time OUT Limited | Health & social care | 2021 |
| Smashpad Group Limited | Wholesale & retail | 2026 |
| Smat Express Limited | Professional & scientific | 2012 |
| SMC Film & Media Limited | Information & communication | 2012 |
| Smdk Freight Ltd | Transport & logistics | 2025 |
| SMH Medics Limited | Health & social care | 2018 |
| Smile Campaigns Limited | Professional & scientific | 2024 |
| Smile Properties Limited | Real estate | 2016 |
| Smile UK Aesthetic Limited | Health & social care | 2025 |
| Smiles by SHB Ltd | Health & social care | 2026 |
| Smith & Bone Properties Limited | Real estate | 2007 |
| Smith Brothers (Tamworth) Properties Limited | Real estate | 1989 |
| Smith Brothers Farms Ltd | Agriculture & fishing | 1997 |
| Smith Rook Limited | Professional & scientific | 2008 |
| Smith Rook Properties Limited | Real estate | 2021 |
| SMK Asset Management Ltd | Real estate | 2023 |
| SMN Kingdom Ltd | Hospitality | 2024 |