| Siyana London Limited | Wholesale & retail | 2017 |
| Sizzle & Smoke Limited | Hospitality | 2026 |
| Sizzle Chicken Ltd | Hospitality | 2024 |
| SJ Stein Properties Limited | Construction | 2012 |
| Sjmm Limited | Administrative & support | 2025 |
| SJO Film Services Limited | Information & communication | 2023 |
| SJS Tax Limited | Professional & scientific | 2006 |
| SK & DK Consultancy Limited | Professional & scientific | 2024 |
| SK Motors Harrow Ltd | Administrative & support | 2024 |
| SK Quality Food Ltd | Hospitality | 2026 |
| SK UK Cars Ltd | Wholesale & retail | 2025 |
| SK Wholesale Vaping Ltd | Wholesale & retail | 2025 |
| Skala Accounting Limited | Professional & scientific | 2011 |
| Skale Advisors Ltd | Financial services | 2020 |
| Skate for London CIC | Education | 2024 |
| Skillbridge Education&Recruitment Services Ltd | Administrative & support | 2024 |
| Skilled Care UK Private Ltd | Health & social care | 2025 |
| Skillsum Ltd | Education | 2018 |
| Skin Surgery and Laser Ltd | Health & social care | 2010 |
| SKIN242 Ltd | Other services | 2022 |
| Skipper Commercial Limited | Professional & scientific | 2008 |
| SKS Property Investments Limited | Real estate | 2023 |
| Sktt Properties Ltd | Real estate | 2022 |
| SKV Consultants Limited | Real estate | 2016 |
| Sky & Blue Care Services Limited | Health & social care | 2020 |
| Sky Blue Carpet and Flooring Ltd | Wholesale & retail | 2024 |
| Sky Developer Ltd | Construction | 2014 |
| Sky London Property Ltd | Real estate | 2024 |
| Sky Star London Ltd | Wholesale & retail | 2025 |
| Sky Surgery Ltd | Health & social care | 2024 |
| Skye Blue Productions Limited | Arts & recreation | 2014 |
| Skygold Advisors Ltd | Financial services | 2020 |
| Skylan Investment Ltd | Real estate | 2021 |
| Skylark Risk and Validation Consulting Ltd | Professional & scientific | 2021 |
| Skyline Build and Management Ltd | Construction | 2025 |
| Skyline Cars & Vans Limited | Wholesale & retail | 2018 |
| Skyline Elite Estate Ltd | Real estate | 2026 |
| Skyline Stay Ltd | Hospitality | 2026 |
| Skyluna Capital Ltd | Construction | 2025 |
| Skymark Investments Limited | Real estate | 2003 |
| Skytwilight Limited | Wholesale & retail | 2026 |
| Skywide Property Limited | Real estate | 2019 |
| Slaconstructionuk Ltd | Construction | 2025 |
| Slams Edgware Limited | Hospitality | 2023 |
| Slash Attire Ltd | Wholesale & retail | 2024 |
| Slcm (FLD) Ltd | Other services | 2008 |
| Sleepy Boobas Ltd | Wholesale & retail | 2023 |
| Slice House Co Ltd | Hospitality | 2026 |
| Slice Hub Limited | Hospitality | 2025 |
| Slick CUT Hairstylist Ltd | Other services | 2024 |
| Slingshot Construction Group Ltd | Construction | 2010 |
| Slingshot Group Limited | Real estate | 2004 |
| Slingshot Property Development Group Ltd | Construction | 2010 |
| Slink Boutique Ltd | Wholesale & retail | 2013 |
| Slink Magazine Limited | Information & communication | 2011 |
| SLM Property Services Ltd | Real estate | 2019 |
| SLS Rail Limited | Construction | 2017 |
| SM Investments 2019 Ltd | Other services | 2019 |
| SM Nathan Limited | Wholesale & retail | 2021 |
| Smart 4 Developments Ltd | Real estate | 2026 |
| Smart Amenity Ltd | Construction | 2016 |
| Smart Apple Ltd | Manufacturing | 2025 |
| Smart Brands Global Ltd | Financial services | 2025 |
| Smart Building Solutions Ltd | Construction | 2017 |
| Smart Capital Properties Limited | Households | 2022 |
| Smart Car Hub Ltd | Wholesale & retail | 2021 |
| Smart Comms Sava Ltd | Construction | 2023 |
| Smart Design Build Limited | Construction | 2025 |
| Smart Eco Engineering Ltd | Water & waste | 2023 |
| Smart Energy Plus Limited | Manufacturing | 2021 |
| Smart Plug Ltd | Construction | 2024 |
| Smart School of Motoring Limited | Education | 2025 |
| Smart Urban Development Ltd | Real estate | 2017 |
| Smart's T & C Limited | Manufacturing | 2019 |
| Smart-Tech Solution (UK) Ltd | Information & communication | 2014 |
| SMART4UP Ltd | Information & communication | 2013 |
| Smartchoice Flooring Solutions Ltd | Construction | 2023 |
| Smartexits Limited | Financial services | 2024 |
| Smartly Done Limited | Other services | 2016 |
| Smartrose Estates Limited | Real estate | 2006 |
| Smartview Estates Limited | Real estate | 2016 |
| Smartwig Ltd | Information & communication | 2023 |
| Smartydigi Ltd | Financial services | 2025 |
| Smash Burger House Ltd | Hospitality | 2026 |
| Smash in Crewe Ltd | Hospitality | 2024 |
| Smashio Colchester Ltd | Hospitality | 2026 |
| Smashio Holloway Limited | Hospitality | 2025 |
| Smashio Ltd | Hospitality | 2025 |
| SMC Studios Ltd | Information & communication | 2005 |
| SME Projects Ltd | Professional & scientific | 2021 |
| Smetanca Ltd | Construction | 2024 |
| SMI3 Consulting Ltd | Health & social care | 2023 |
| Smile With Style Limited | Health & social care | 2008 |
| SMILE64 Limited | Health & social care | 2014 |
| Smilecare Aesthetics Limited | Health & social care | 2012 |
| Smiles for Miles Travel Ltd | Administrative & support | 2020 |
| Smith ET Anketell Change Ltd | Administrative & support | 1998 |
| Smithson Ltd. | Wholesale & retail | 2000 |
| Smitty Properties Ltd | Real estate | 2020 |
| SMJ Consultants & Management Ltd | Professional & scientific | 2024 |