| Securelondonlocksmiths Ltd | Other services | 2024 |
| SED Vera Limited | Professional & scientific | 2014 |
| Seebeyond Coaching Limited | Administrative & support | 2025 |
| Self Technologies Ltd | Manufacturing | 2024 |
| Seminal Associates Limited | Professional & scientific | 2007 |
| Senatus Partners Ltd | Professional & scientific | 2006 |
| Sensor Consulting Limited | Information & communication | 2003 |
| Sequentis Health Limited | Professional & scientific | 2018 |
| Serendipity INT Ltd | Information & communication | 2010 |
| Serpil Aesthetics Ltd | Health & social care | 2022 |
| Sersu Limited | Hospitality | 2016 |
| Setenergy Limited | Professional & scientific | 2024 |
| Sew-What Online Limited | Education | 2018 |
| Sfweu Ltd | Information & communication | 2023 |
| SGK Associates Ltd | Real estate | 2024 |
| Shacklegate Ltd | Real estate | 2024 |
| Shackleton Consulting Limited | Professional & scientific | 2020 |
| Shady Cabal Ltd | Information & communication | 2017 |
| Shanti Limited | Professional & scientific | 1998 |
| Shaolin Wheel of Life Limited | Arts & recreation | 2003 |
| Sharp Studios Limited | Information & communication | 2024 |
| Sheen Property Limited | Financial services | 2016 |
| Sherborne Court (Hampton) Residents Company Limited | Households | 1991 |
| Sherin Management Services Limited | Professional & scientific | 2004 |
| Shirley View Nursing Home Limited | Other services | 2023 |
| Shoot and Roll Ltd | Information & communication | 2023 |
| Showcase Hire International Limited | Wholesale & retail | 1998 |
| Shpeter Productions Ltd | Information & communication | 2022 |
| SHY Bairn Design Limited | Arts & recreation | 2022 |
| Sidra One Ltd | Hospitality | 2016 |
| Sigma Commercial Ltd | Professional & scientific | 2022 |
| Simlowe Property Limited | Real estate | 2016 |
| Simon Kirby and Associates Ltd | Wholesale & retail | 2019 |
| Simpler Ltd | Professional & scientific | 2018 |
| Sirluxe Socks Ltd | Wholesale & retail | 2020 |
| SIX (Teddington) Ltd | Other services | 2025 |
| SIX Miles High Limited | Professional & scientific | 2017 |
| Sixth Degree Tech Ltd | Professional & scientific | 2022 |
| SJE Consultancy Limited | Professional & scientific | 2025 |
| Sjoeven Ltd | Extraterritorial | 2025 |
| Sjwhittaker Consulting Ltd | Health & social care | 2014 |
| Skarp Limited | Professional & scientific | 2025 |
| Skiltran Limited | Professional & scientific | 1987 |
| Skinfit Spa Ltd | Other services | 2018 |
| Skinner Associates Limited | Professional & scientific | 2013 |
| SKK Consultants Limited | Professional & scientific | 2017 |
| Skylights Conversions Ltd | Construction | 2016 |
| Skyline Fitout Ltd | Construction | 2013 |
| Skypack Limited | Transport & logistics | 2015 |
| Slade Fitness Limited | Arts & recreation | 2023 |
| Smart Korr Limited | Information & communication | 2017 |
| Smart Protect Group UK Ltd | Wholesale & retail | 2021 |
| Smarter Furniture Ltd | Manufacturing | 2013 |
| SMC Growth Partners Ltd | Professional & scientific | 2025 |
| Smidt Ltd | Construction | 2007 |
| Smith & Irwin Property Solutions Ltd | Real estate | 2024 |
| Smoking Roses Productions Ltd | Arts & recreation | 2023 |
| Sneller Group Holdings Limited | Real estate | 2016 |
| Sneller Property Consultants Limited | Real estate | 1991 |
| Snellers Limited | Real estate | 2010 |
| SNK Retail Group Ltd | Wholesale & retail | 2026 |
| Soar Worldwide Limited | Other services | 2019 |
| Soaring Digital Ltd | Wholesale & retail | 2020 |
| Social Playground Ltd | Arts & recreation | 2022 |
| Society for Reproduction and Fertility | Professional & scientific | 1960 |
| Solarnetix Ltd | Construction | 2025 |
| Solid Engineering and Consultancy Ltd | Professional & scientific | 2024 |
| Solid Matter Limited | Construction | 2015 |
| Soluis Growth Ltd | Professional & scientific | 2026 |
| Som.X Limited | Professional & scientific | 2019 |
| Sonata Ventures Ltd | Professional & scientific | 2025 |
| Sophie Aukett Limited | Professional & scientific | 2025 |
| South Court Residents Limited | Households | 1989 |
| South Derry Construction Limited | Construction | 2017 |
| South Design Ltd. | Professional & scientific | 2000 |
| South West Carpenters Limited | Construction | 2013 |
| Southern Electric Traction Group C.I.C. | Manufacturing | 2018 |
| Southmead Gardens Management Limited | Households | 2006 |
| Sovereign House Estates Limited | Other services | 1988 |
| Spa Nails TW11 Ltd | Other services | 2024 |
| Spare Street Limited | Arts & recreation | 2020 |
| Spare Street Studios Limited | Real estate | 2025 |
| Sparkes Consulting Limited | Information & communication | 2017 |
| Spearhead Consultancy Limited | Professional & scientific | 2012 |
| Spearhead IT Consultancy Limited | Information & communication | 2010 |
| Specialist Training Solutions (UK) Ltd | Arts & recreation | 2012 |
| Spencer & Wedekind Ltd | Construction | 2013 |
| Spencer Park Court Management Company Limited | Households | 1981 |
| Spirit Media Studios Limited | Information & communication | 2020 |
| Spirit Studios One Limited | Information & communication | 2026 |
| SPK Electrical Service Limited | Construction | 2021 |
| Splicing Limited | Information & communication | 2021 |
| Sportready Ltd | Education | 2018 |
| SQU Consulting Ltd | Professional & scientific | 2018 |
| Squadrato Limited | Professional & scientific | 2019 |
| Squirrel Tech Ltd | Information & communication | 2025 |
| Sqzr Ltd | Manufacturing | 2025 |
| SS London Solution Ltd | Manufacturing | 2026 |
| ST Aqua Engineering Limited | Professional & scientific | 2007 |
| ST Georges Recruitment Limited | Administrative & support | 2013 |