| Skiing Holidays Ltd. | Administrative & support | 2003 |
| Skillfull Ltd | Information & communication | 2011 |
| Skillicorn Anderson Associates International Ltd | Agriculture & fishing | 2015 |
| Skims UK International Ltd | Wholesale & retail | 2024 |
| Skin Trinity Ltd | Other services | 2016 |
| Skinfinity by Hiba Rihan Ltd | Other services | 2021 |
| Skinner & Vale Limited | Wholesale & retail | 2024 |
| Skonzo Limited | Information & communication | 2014 |
| Skyap Properties Limited | Real estate | 2025 |
| Skyhans Ltd | Manufacturing | 2024 |
| Skyline Homes Developments Limited | Construction | 2024 |
| Skyline Outdoor Limited | Construction | 2021 |
| Skyloh Limited | Real estate | 2021 |
| Skytrak Consulting Limited | Information & communication | 2021 |
| Slawomir Bilik Ltd | Construction | 2014 |
| Sleeping Mountain Limited | Other services | 2005 |
| SLH Legal Services Limited | Professional & scientific | 2014 |
| Sloma Investment Group Ltd | Information & communication | 2018 |
| Slotworthy Property Management Limited | Administrative & support | 1988 |
| SLP Club Investment Corporation Limited | Professional & scientific | 2020 |
| SMA Bakery and Patisserie Limited | Manufacturing | 2022 |
| Small AXE Communications Ltd | Information & communication | 2011 |
| Small BUT Busy Limited | Wholesale & retail | 2025 |
| Smart Care Solutions Ltd | Information & communication | 2021 |
| Smart Hyperion Limited | Information & communication | 2024 |
| Smart London Collection Ltd | Wholesale & retail | 2024 |
| Smart Pharmasolutions Ltd | Wholesale & retail | 2023 |
| Smart Sems Limited | Transport & logistics | 2025 |
| Smartbuild Property Ltd | Construction | 2020 |
| Smartcell Solution Ltd | Wholesale & retail | 2025 |
| Smashkeema Limited | Hospitality | 2024 |
| Smith's Yard Management Limited | Real estate | 1988 |
| SMK Associates UG Limited | Information & communication | 2014 |
| Smok'D - Britannia Limited | Hospitality | 2020 |
| Smok'D - Grey Horse Ltd | Hospitality | 2024 |
| Smok'D - Vauxhall Ltd | Hospitality | 2025 |
| Snig Estates Ltd | Real estate | 2020 |
| SNL Bistro Ltd | Hospitality | 2016 |
| SNM Healthcare Limited | Health & social care | 2013 |
| Snobs & Cobblers Limited | Other services | 2021 |
| Snooty FOX Shalford Limited | Administrative & support | 2015 |
| Snooty's Groceries Limited | Administrative & support | 2013 |
| Snow White Cleaners Limited | Administrative & support | 2012 |
| Snowball Interactive Ltd | Information & communication | 2025 |
| SNS Dental Practice Limited | Health & social care | 2015 |
| SO Jorgeous Ltd | Wholesale & retail | 2014 |
| Soames House Ltd | Hospitality | 2021 |
| Sobr Ltd | Professional & scientific | 2025 |
| Sobriquet Group Limited | Administrative & support | 2023 |
| Social Byte Technology Limited | Information & communication | 2023 |
| Soft EGG Limited | Information & communication | 2007 |
| Software Education Limited | Education | 2017 |
| Software Modernization Technologies Limited | Information & communication | 2010 |
| Sohmarketing Ltd | Professional & scientific | 2025 |
| Solarco Software Limited | Information & communication | 2004 |
| Soledoarts Ltd | Professional & scientific | 2019 |
| Solent Surgical Specialist Partnership LLP | | 2019 |
| Solid Securities LLP | | 2014 |
| Solid State Media Limited | Information & communication | 2010 |
| Solum Governance Ltd | Information & communication | 2025 |
| Solution Tribute Limited | Information & communication | 2011 |
| Solutions by Ibby Limited | Information & communication | 2009 |
| Solutions for Health & Social Care Ltd | Administrative & support | 2018 |
| Solutions Staffing Ltd | Administrative & support | 2024 |
| Solutionsstudio Ltd | Administrative & support | 2025 |
| Solvex Capital Limited | Real estate | 2019 |
| Somesense Limited | Information & communication | 2020 |
| Somo Group Ltd | Financial services | 2022 |
| Sonu Ashok Limited | Health & social care | 2019 |
| Sophie Bates Architects Limited | Professional & scientific | 2010 |
| Sophie Herald Studio Ltd | Construction | 2024 |
| Soteng Ltd | Professional & scientific | 2021 |
| Soul Chakra Holdings Limited | Financial services | 2018 |
| Soul Chakra Ltd | Arts & recreation | 1992 |
| Source 4 Personnel Solutions Limited | Administrative & support | 1993 |
| South East London Doctors Co Operative Limited | Health & social care | 1996 |
| South London Food Ltd | Hospitality | 2019 |
| South West Surrey Properties Limited | Construction | 2003 |
| Southbank Lodge Management Limited | Households | 1994 |
| Southcoast Digital Limited | Information & communication | 2026 |
| Southcote Healthcare Solutions Ltd | Manufacturing | 2014 |
| Southdown Apiaries Ltd | Agriculture & fishing | 2023 |
| Southern Audio Services Limited | | 1970 |
| Southlands College Estate Wimbledon Limited | Administrative & support | 2013 |
| Southlands Parkside Residents Management Company Limited | Households | 2011 |
| Southlea Consulting Limited | Information & communication | 2026 |
| Southmead Power Services Ltd | Professional & scientific | 2019 |
| Southshore AD Limited | Professional & scientific | 2025 |
| Southwest Kitchens Limited | Wholesale & retail | 2017 |
| Sova (London) Ltd | Hospitality | 2015 |
| Sovian Epublishing Limited | Administrative & support | 2025 |
| SOW HOW Tarn Escapes Limited | Hospitality | 2021 |
| SP Costs & Law Limited | Professional & scientific | 2019 |
| SP Digital Limited | Information & communication | 2017 |
| SP97 Ltd | Real estate | 2023 |
| Spacemaking Limited | Construction | 2018 |
| Spacenet IT Ltd | Information & communication | 2010 |
| Spacs Consultancy Limited | Professional & scientific | 2018 |
| Spaks Services Limited | Information & communication | 2021 |
| Spark Productions Limited | Arts & recreation | 1993 |