| Silverfern House Limited | Professional & scientific | 2014 |
| Silverstar Packaging Limited | Wholesale & retail | 2020 |
| Silverstone Finance Limited | Financial services | 2025 |
| Simart Management Limited | Administrative & support | 2015 |
| Simcomm Ltd | Information & communication | 2012 |
| Simitri Studio Ltd | Other services | 2026 |
| Simon Atkins Media Limited | Information & communication | 2013 |
| Simple Networks and Distributions Limited | Administrative & support | 2017 |
| Simplex Mortgages Ltd | Financial services | 2020 |
| Simplistic Developments Limited | Real estate | 2022 |
| Simplix Property Limited | Real estate | 2021 |
| Simply Consultancy Limited | Professional & scientific | 2020 |
| Simply Hire Limited | Administrative & support | 1998 |
| Simply LMD Ltd | Administrative & support | 2012 |
| Simran Foods Limited | Households | 2011 |
| Singer Beverages Limited | Hospitality | 2017 |
| Siraj Limited | Other services | 2018 |
| Siren Grounds Collective Ltd | Wholesale & retail | 2025 |
| Sirko Consulting Limited | Professional & scientific | 2011 |
| Sirrah Bespoke Ltd | Administrative & support | 2021 |
| SIS Enforcement Ltd | Professional & scientific | 2016 |
| Siteforce Labour Hire Ltd | Construction | 2025 |
| Sivan Arul - Humanity | Other services | 2005 |
| Sivyer Jennings Ltd | Financial services | 2019 |
| SIX Dots Ltd | Professional & scientific | 2023 |
| SJ Gudgeon Limited | Professional & scientific | 2007 |
| SJA Optical Ltd | Wholesale & retail | 2025 |
| SJC87 Initiative UK | Health & social care | 2020 |
| SJH Events Limited | Information & communication | 2026 |
| SJH Studios Limited | Information & communication | 2024 |
| SJR Entertainment Limited | Information & communication | 2024 |
| SK Civil Engineering Ltd | Construction | 2012 |
| SK Trade Wholesale Ltd | Wholesale & retail | 2025 |
| Skalboy Enterprises Limited | Arts & recreation | 1997 |
| SKC Media Entertainment Limited | Arts & recreation | 2025 |
| Skilled Build London Ltd | Construction | 2023 |
| Skilled Build Ltd | Construction | 2023 |
| Skillion Limited | Real estate | 2025 |
| SKL Business Ltd | Wholesale & retail | 2020 |
| SKN HQ Ltd | Professional & scientific | 2024 |
| SKN RX Limited | Other services | 2025 |
| Skylight Group Limited | Administrative & support | 2018 |
| Skyline Consulting Services Ltd | Health & social care | 2017 |
| Skyview Investments Limited | Real estate | 2006 |
| Sl-Tech Ltd | Information & communication | 2012 |
| SLD Built West Ltd | Construction | 2014 |
| Slobsession Ltd | Wholesale & retail | 2023 |
| SLR Supplies Ltd | Wholesale & retail | 2011 |
| SM Global Solutions Ltd | Wholesale & retail | 2020 |
| SM3 Limited | Information & communication | 2013 |
| SM3 United Ltd | Wholesale & retail | 2021 |
| Smart Build Developments Limited | Construction | 2006 |
| Smart Build Investments Ltd | Real estate | 2018 |
| Smartek Solutions Ltd | Wholesale & retail | 2022 |
| Smartspectra Limited | Professional & scientific | 2024 |
| Smarty Pants Abbey Lane Limited | Financial services | 2021 |
| Smile Care by A.S. Ltd | Health & social care | 2026 |
| Smile Everyday Ltd | Health & social care | 2014 |
| Smile Intellect Limited | Health & social care | 2026 |
| Smiley Day Ltd | Information & communication | 2023 |
| Smiling Stars Foundation | Health & social care | 2023 |
| Smiths Wholesale Ltd | Wholesale & retail | 2023 |
| SMS Property Solutions Ltd | Real estate | 2021 |
| Smurthwaite Financial Services Limited | Financial services | 2025 |
| Snapcollect Limited | Transport & logistics | 2025 |
| Snapgroup Technology Limited | Information & communication | 2018 |
| Snow White Launderettes Limited | Real estate | 1981 |
| SNS Constructions London Ltd | Construction | 2019 |
| SNS Local - Woodford Green Ltd | Wholesale & retail | 2024 |
| SO Cloud Media Limited | Information & communication | 2018 |
| Sobha SEN & Sons Limited | Real estate | 2013 |
| Sobha Sivaprasad Limited | Health & social care | 2013 |
| Soccer Student Pathway Ltd | Administrative & support | 2021 |
| Social Dynamics Ltd | Administrative & support | 2019 |
| Social Placement Limited | Professional & scientific | 2011 |
| Sodhi Real Estate Ltd | Real estate | 2021 |
| Sofdar Construct Ltd | Construction | 2013 |
| Sofia BNB Ltd | Construction | 2025 |
| Software Object Ltd | Professional & scientific | 2025 |
| Soho Building & Maintenance Ltd | Construction | 2015 |
| Sokell Ltd | Information & communication | 2017 |
| Sokolov Consulting Ltd | Professional & scientific | 2023 |
| Solar Display Limited | Professional & scientific | 1984 |
| Solar Green Energy Services Limited | Wholesale & retail | 2018 |
| Solasta Wealth Management Ltd | Professional & scientific | 2019 |
| Soldup Limited | Extraterritorial | 2020 |
| Solego Limited | Construction | 2025 |
| Solidaire Property Group Limited | Professional & scientific | 2019 |
| Solihull Productions Ltd | Arts & recreation | 2015 |
| Sologate Consultants Limited | Transport & logistics | 2026 |
| SOLUTIONS67 Ltd | Information & communication | 2022 |
| Somac Lettings Limited | Real estate | 2012 |
| Somaro Limited | Professional & scientific | 2014 |
| SON Properties Limited | Real estate | 2025 |
| Sonicade Music Group Limited | Administrative & support | 2022 |
| Sons of Academy Limited | Education | 2020 |
| Sopica Limited | Professional & scientific | 2004 |
| Soraya Limited | Real estate | 2003 |
| Sorion Partners Limited | Administrative & support | 2026 |
| Soulho Ltd | Wholesale & retail | 2026 |