| Slough Project Ltd | Hospitality | 2021 |
| Slow Burn Ritual Ltd | Manufacturing | 2026 |
| Slusportsmgmt Limited | Professional & scientific | 2017 |
| SM Wine Services Ltd | Hospitality | 2023 |
| Smak Burgers & Shakes Ltd | Hospitality | 2022 |
| Small Jobs R US Limited | Construction | 2017 |
| Small Kiwi Cloud Gardens Ltd | Information & communication | 2026 |
| Small World Cinema CIC | Education | 2021 |
| Smart Building GP Limited | Construction | 2017 |
| Smart Buildings Controls Ltd | Construction | 2026 |
| Smart Cookies Productions Ltd | Information & communication | 2025 |
| Smart Extra Space Ltd | Construction | 2017 |
| Smart Installers Ltd | Professional & scientific | 2025 |
| Smart Look EYE Care Limited | Other services | 2009 |
| Smart LX Ltd | Construction | 2013 |
| Smart Reflectors Ltd | Wholesale & retail | 2022 |
| Smart Surfacing Solutions Ltd | Construction | 2022 |
| Smart T'S Limited | Professional & scientific | 2003 |
| Smart's Food & Wine Ltd | Wholesale & retail | 2015 |
| SMART4LIFE Ltd | Real estate | 2024 |
| Smarteats Limited | Hospitality | 2024 |
| Smartey Mastery Ltd | Professional & scientific | 2023 |
| Smash IT Rage Room Ltd | Arts & recreation | 2022 |
| SME Audit Services Ltd | Financial services | 2013 |
| Smech Mechanical Services Ltd | Professional & scientific | 2019 |
| SMG Consultancy Solutions Limited | Information & communication | 2018 |
| SMG Projects Care Limited | Health & social care | 2023 |
| Smith Builders (London) Limited | Other services | 2012 |
| Smithonpurpose Ltd | Professional & scientific | 2017 |
| Smiths Roofing Services Limited | Construction | 2024 |
| SMJ Lettings & Developments Ltd | Construction | 2019 |
| SMK Electrical Services Ltd | Construction | 2022 |
| Smok and Mobile Ltd | Manufacturing | 2019 |
| Smooth Rides Limited | Transport & logistics | 2023 |
| Smoothclassics Ltd | Information & communication | 2012 |
| SMS Construction Services Limited | Construction | 2015 |
| SMT Maintenance Limited | Construction | 2018 |
| Snake Property (Investments) Limited | Real estate | 1997 |
| Snap Feedback Ltd | Professional & scientific | 2017 |
| Snaple Ltd | Real estate | 2017 |
| Snarl Holdings Limited | Real estate | 2024 |
| Snazzy Crafty Ltd | Other services | 2025 |
| Sneakrs+ Ltd | Wholesale & retail | 2026 |
| Snodashiq Limited | Information & communication | 2025 |
| Snowball Homes Ltd | Real estate | 2025 |
| Snowchains Limited | Wholesale & retail | 1982 |
| Snowy London Ltd | Extraterritorial | 2026 |
| SNT Coffe Ltd | Hospitality | 2025 |
| Sntw Property Limited | Real estate | 2026 |
| Snuggle Snout Ltd | Wholesale & retail | 2024 |
| Snyman and Summit Ltd | Professional & scientific | 2025 |
| SO Lawson London Ltd | Professional & scientific | 2023 |
| SO Odiase Property Management Limited | Financial services | 2026 |
| Soames Limited | Real estate | 2005 |
| Social Bull Hospitality Ltd | Hospitality | 2026 |
| Social Housing Support Services Ltd | Real estate | 2025 |
| Social Never Sleeps Limited | Professional & scientific | 2026 |
| Socialize Academy of Marketing Limited | Professional & scientific | 2024 |
| Sociallystyled Ltd | Professional & scientific | 2025 |
| Sociera Limited | Information & communication | 2023 |
| Socrates Consulting Ltd | Other services | 2023 |
| Soffte.Ai Ltd | Information & communication | 2026 |
| Sofia Med-Food Limited | Hospitality | 2024 |
| Softpower Consultancy Limited | Information & communication | 1995 |
| Software Simulations International Ltd. | Information & communication | 1993 |
| Software Topco Limited | Information & communication | 2021 |
| Sogim 3 Limited | Wholesale & retail | 2020 |
| Sogim Limited | Wholesale & retail | 2007 |
| Soji Commodity Trading Ltd | Manufacturing | 2014 |
| Sola Life Management Ltd | Other services | 2023 |
| Solar Chemicals Limited | Wholesale & retail | 1980 |
| Solaratech Ltd | Construction | 2023 |
| Solarfair Ltd | Construction | 2022 |
| Solaris Horizons Ltd | Professional & scientific | 2025 |
| Solena Atelier Ltd | Wholesale & retail | 2025 |
| Solent House Management Limited | Households | 2000 |
| Solid Property Investments Limited | Real estate | 2015 |
| Solidrock UK Limited | Information & communication | 2000 |
| Solidwilsonbuilders Ltd | Construction | 2026 |
| Soloye Entreprise Ltd | Hospitality | 2019 |
| Solution Trade Partners LLP | | 2023 |
| Solving Futures Limited | Health & social care | 2024 |
| Solving Homes Limited | Health & social care | 2020 |
| Sona Property Developments Limited | Construction | 2015 |
| Sonata Technology Ltd | Information & communication | 2020 |
| Sonia Torosyan-Compton Ltd | Professional & scientific | 2019 |
| Sonicjoy Solutions Limited | Information & communication | 2023 |
| Sonne PR Ltd | Arts & recreation | 2016 |
| Sonus Trading Ltd | Wholesale & retail | 2023 |
| Sonya Karafistan Consulting Ltd | Professional & scientific | 2012 |
| Soodans Ltd | Health & social care | 2018 |
| Soontobeannounced Ltd | Wholesale & retail | 2022 |
| Sophia and William (Rotherhithe) RTM Company Limited | Real estate | 2026 |
| Sophia Square (Rotherhithe) RTM Company Limited | Real estate | 2026 |
| Sophia Square 2 (Rotherhithe) RTM Company Limited | Real estate | 2026 |
| Sophie Craig Limited | Professional & scientific | 2018 |
| Soragram Ltd | Manufacturing | 2012 |
| Sorby Brown Designs Ltd | Professional & scientific | 2023 |
| Sorted Plumbing and Heating Ltd | Construction | 2026 |
| SOS Consulting Ltd | Information & communication | 2023 |