| Simfin Financial Limited | Financial services | 2018 |
| Simone Foley (Tuition) Limited | Education | 2017 |
| Simply B Energy Ltd | Administrative & support | 2024 |
| Simply CAD Limited | Information & communication | 2005 |
| Simply Ella Beauty and Wellbeing Ltd | Other services | 2018 |
| Simply Folders Ltd | Manufacturing | 2021 |
| Simply Gabriella Limited | Professional & scientific | 2022 |
| Simply Mediation Limited | Professional & scientific | 2016 |
| Simply Paye Limited | Administrative & support | 2018 |
| Simpson Welding & Fabrication Engineering Limited | Manufacturing | 2019 |
| Sinamor Limited | Information & communication | 2010 |
| SIP Trader Limited | Information & communication | 2005 |
| Sirius Prime Ltd | Professional & scientific | 2013 |
| Sisyphus Consulting Limited | Information & communication | 2024 |
| Site Clearance Ltd | Construction | 2021 |
| Site Ctrl Ltd | Professional & scientific | 2025 |
| Site Orex Limited | Wholesale & retail | 2024 |
| SIX the Mews Limited | Real estate | 2017 |
| Sixredsquares Limited | Information & communication | 2011 |
| Sixtysix (Southend) Ltd | Real estate | 2023 |
| SJ Builders Ltd | Construction | 2018 |
| SJ Hart Holdings Ltd | Wholesale & retail | 2023 |
| SJ Holdco Limited | Financial services | 2026 |
| SJC Heritage Limited | Financial services | 2020 |
| SJC One Limited | Professional & scientific | 2016 |
| Sjle Property Developments Limited | Construction | 2020 |
| Sjle Property Investment Limited | Real estate | 2023 |
| Sjle Property Limited | Construction | 2021 |
| SJP Recovery Solutions Ltd | Administrative & support | 2013 |
| SJW DS Consultancy Ltd | Information & communication | 2025 |
| SJW Mortgages Ltd | Financial services | 2017 |
| SKA Projects Limited | Professional & scientific | 2016 |
| Skeates & Partners Limited | Professional & scientific | 2018 |
| SKI Chalets Morzine Limited | Administrative & support | 2005 |
| Skill Electrical Mechanical Ltd | Construction | 2022 |
| Skilled Giafg Ltd | Construction | 2021 |
| Skin 2 Skin Ltd | Other services | 2025 |
| Skinbio Aesthetics Ltd | Health & social care | 2024 |
| Skincentrix Limited | Health & social care | 2023 |
| Skinolgy Ltd | Health & social care | 2026 |
| Skippr Data Ltd | Wholesale & retail | 2020 |
| Skky Ltd | Real estate | 2025 |
| Sky Top Lofts Ltd | Construction | 2023 |
| Sky Top Roofing Limited | Construction | 2021 |
| Sky Vision Drones UK Ltd | Professional & scientific | 2025 |
| Skyarc Developments Ltd | Real estate | 2026 |
| Skye Marine Welding & Fabrication Ltd | Manufacturing | 2021 |
| Skye's the Limit Developments Limited | Construction | 2021 |
| Skye's the Limit Limited | Real estate | 2021 |
| Skyline Elevators London Limited | Professional & scientific | 2022 |
| SL Chauffeurs Limited | Transport & logistics | 2023 |
| SL Essex Ltd | Hospitality | 2025 |
| SL Stone and Ceramics Ltd | Construction | 2017 |
| Slade Stone Limited | Manufacturing | 2025 |
| Slamming Forth Ltd | Information & communication | 2022 |
| Slender Pictures Limited | Information & communication | 2013 |
| SLH Law Ltd | Professional & scientific | 2022 |
| SLM Accountants & Tax Advisors Limited | Professional & scientific | 2014 |
| SLM Hold Co Limited | Financial services | 2022 |
| Slowley Property Group Limited | Real estate | 2026 |
| Slowley Property Holdings Limited | Real estate | 2023 |
| SLP Consulting Limited | Information & communication | 2014 |
| Slush Rush Ltd | Extraterritorial | 2021 |
| SLV Group Staffing Partners Limited | Administrative & support | 2023 |
| SM Home Properties Limited | Real estate | 2024 |
| Small Acorn Wealth Ltd | Financial services | 2025 |
| Smart Build Property Solutions Limited | Construction | 2019 |
| Smartdroiddev Ltd | Information & communication | 2019 |
| Smiling Ltd | Information & communication | 2024 |
| Smitten With Sun Ltd | Other services | 2022 |
| SMM Group Ltd | Information & communication | 2019 |
| SMO Properties Ltd | Real estate | 2018 |
| SMR Info Solutions Limited | Information & communication | 2013 |
| SMR Nest Ltd | Real estate | 2025 |
| SNM Trans Concrete Limited | Transport & logistics | 2014 |
| Social by Kennedy Limited | Administrative & support | 2025 |
| Social IT. NOW Limited | Manufacturing | 2024 |
| Social Staffing Limited | Administrative & support | 2020 |
| Social Work Solutions (South East) Ltd | Health & social care | 2021 |
| Socially Enterprise Limited | Information & communication | 2021 |
| Sofine Beauty House & Co Limited | Transport & logistics | 2026 |
| Softline UK Limited | Information & communication | 1989 |
| Software Devices Limited | Information & communication | 1991 |
| Sojo Consultants Limited | Professional & scientific | 2024 |
| Solanki Investments Limited | Financial services | 2024 |
| Solar 4 YOU Limited | Construction | 2021 |
| Solar Essex Ltd | Construction | 2025 |
| Solar Windows & Doors Limited | Other services | 2005 |
| Solex Legal Services Limited | Professional & scientific | 2010 |
| Solex Sun Care Limited | Wholesale & retail | 2025 |
| Solex Sun Protection Limited | Wholesale & retail | 2017 |
| Solis Home UK Ltd | Wholesale & retail | 2019 |
| Soltiamo Records Ltd | Information & communication | 2023 |
| Solëina Limited | Arts & recreation | 2022 |
| Somerwood Property Management Company Limited | Administrative & support | 2013 |
| Something Creative LDN Ltd | Information & communication | 2019 |
| Sona Short Lets Ltd | Hospitality | 2025 |
| Songard Limited | Manufacturing | 2024 |
| Sonny Public Relations Limited | Professional & scientific | 2024 |
| Sonray Plumbing Ltd | Construction | 2021 |