| Satnam Sakhi Ltd | Wholesale & retail | 2023 |
| SAW Construction Ltd | Construction | 2016 |
| Saya Aesthetics Limited | Health & social care | 2019 |
| Sayers Carpentry and Building Ltd | Construction | 2009 |
| SBP Land Limited | Real estate | 2011 |
| SBS London Ltd | Other services | 2023 |
| Scjl Properties Ltd | Real estate | 2022 |
| Scope Movement Ltd | Other services | 2024 |
| Scorpion Limited | Professional & scientific | 2001 |
| Scorpion Research Limited | Professional & scientific | 1994 |
| Scott Dixon Equestrian Ltd | Arts & recreation | 2025 |
| Scouting UK Ltd | Other services | 2022 |
| Scroom Limited | Administrative & support | 2015 |
| Scruffy Lookin' Limited | Extraterritorial | 2010 |
| SD Building Plans Limited | Professional & scientific | 2015 |
| SDR Innovations UK PVT Ltd | Administrative & support | 2022 |
| Sea King UK Limited | Manufacturing | 2016 |
| Seabrook Graham Limited | Construction | 2014 |
| Sean Jones Creative Studio Ltd | Professional & scientific | 2024 |
| Seascale Group Ltd | Health & social care | 2023 |
| Seasons (UK) Limited | Other services | 2006 |
| SEB Financial Services Limited | Financial services | 2006 |
| Sebastian Carpentry and Joinery Limited | Manufacturing | 2023 |
| Seed Publishing Limited | Professional & scientific | 2003 |
| Selsdon Veterinary Surgery Ltd | Professional & scientific | 2025 |
| Seraphin Ventures Ltd | Manufacturing | 2026 |
| Serendipitee Limited | Real estate | 2010 |
| Serenity UK Care Rehab Limited | Health & social care | 2022 |
| Serv-Ice Refrigeration Limited | Manufacturing | 2008 |
| SET Focus Ltd | Information & communication | 2024 |
| Setpoint Capital Limited | Professional & scientific | 2022 |
| Seven Star Media Limited | Other services | 2017 |
| Sevenoaks Orthotics Consultancy Limited | Health & social care | 2022 |
| Sevenoaks Plumbers Ltd | Construction | 2023 |
| Sewclean (UK) Limited | Other services | 2006 |
| Seymour Public Relations Ltd | Professional & scientific | 2012 |
| SFK Developments Limited | Construction | 2014 |
| SGF Electrical Contractors Limited | Construction | 2024 |
| Sgjp Consulting Ltd | Professional & scientific | 2025 |
| SGK Office Furniture Limited | Administrative & support | 2016 |
| Sgss Consulting Ltd | Professional & scientific | 2025 |
| Shalford Pears (Property) Limited | Construction | 1998 |
| Shan Enterprisess Ltd | Wholesale & retail | 2014 |
| Sharp Design Limited | Information & communication | 2006 |
| Sharratts (London) LLP | | 2010 |
| Shine a Light Media Limited | Other services | 2012 |
| Shipping and Airlines Limited | Transport & logistics | 1944 |
| Shops 4 US Ltd | Wholesale & retail | 2022 |
| Sidcup Plumbing and Heating Ltd | Construction | 2020 |
| Silver Oaks Consulting Ltd | Professional & scientific | 2021 |
| Silvergriffen Consulting Ltd | Information & communication | 2020 |
| Silverwood Financial Solutions Ltd | Financial services | 2012 |
| Silverwood Pension Solutions Ltd | Financial services | 2024 |
| Simon Collins Ltd | Professional & scientific | 2016 |
| Simply Legislation Ltd | Construction | 2021 |
| Simply Sports Trading Cards Ltd | Wholesale & retail | 2023 |
| Single Street Limited | Manufacturing | 2024 |
| Sirkis Strategy Limited | Professional & scientific | 2025 |
| Sisu Engineering Limited | Professional & scientific | 2018 |
| Site Acres Limited | Construction | 2010 |
| Site Security Services (London) Limited | Construction | 1999 |
| SIX Degrees Projects Ltd | Professional & scientific | 2014 |
| SIX Keys Partnership Ltd | Information & communication | 2021 |
| SJ Corporation Limited | Construction | 2013 |
| SJC Electrical & Maintenance Ltd | Construction | 2012 |
| SJH 1969 Limited | Administrative & support | 2014 |
| SJO Consultancy Services Ltd | Public administration | 2019 |
| Skeels Advisory Limited | Professional & scientific | 2016 |
| Skinny Dipped Films Limited | Information & communication | 2018 |
| Skinology Aesthetic Clinic Ltd | Other services | 2025 |
| SKN Reset by Nicole Ltd | Other services | 2026 |
| Skyeportal Ltd | Information & communication | 2019 |
| Skywing Aviation Services Limited | Transport & logistics | 2026 |
| SL Elec Ltd | Construction | 2012 |
| SLJ House and Garden Build Ltd | Construction | 2019 |
| Sloane Flooring Ltd | Construction | 2018 |
| Sloane Gardens Residential Limited | Real estate | 1984 |
| SLR Recruitment Services Ltd | Administrative & support | 2024 |
| SM Cleaning & Support Services Ltd | Other services | 2010 |
| Smaga Bakery Limited | Information & communication | 2013 |
| Small Jobs Electrical Ltd | Construction | 2020 |
| Smart Resources Recycling Limited | Administrative & support | 2016 |
| SMD Creative Ltd | Professional & scientific | 2018 |
| Smith & Young Sales Limited | Wholesale & retail | 1994 |
| Smiths Developments (Bromley) Limited | Construction | 2016 |
| Smiths of Bromley Limited | Construction | 2006 |
| Smithson Rail Electrification Ltd | Professional & scientific | 2014 |
| Smyth Bros. (Developments) Limited | Construction | 1975 |
| Smyth Bros. (Formwork) Limited | Construction | 1969 |
| SNB Creative Ltd | Administrative & support | 2024 |
| Social Media Sisters Ltd | Professional & scientific | 2025 |
| Societas Talent Ltd | Administrative & support | 2024 |
| Solar Plus Ltd | Energy | 2008 |
| Solent Spirit (Hampshire) Ltd | Wholesale & retail | 2021 |
| Solutions On-Site(London) Limited | Extraterritorial | 2009 |
| Sonar Minds Consulting Limited | Financial services | 2024 |
| Sonic Cleaning Services Kent Ltd | Administrative & support | 2025 |
| Sonnexus Ltd | Professional & scientific | 2023 |
| South East Electrician Service Ltd | Construction | 2025 |
| South East London & Kent Ambulance Service Ltd | Health & social care | 2025 |