| Smile IT Solutions Limited | Information & communication | 2015 |
| Smile Success Ltd | Health & social care | 2022 |
| Smilecare Dental Practice Limited | Health & social care | 2019 |
| Smilecare Developments Limited | Professional & scientific | 2022 |
| Smiles and Sleep Ltd | Health & social care | 2025 |
| Smilewell Dental Limited | Health & social care | 2022 |
| Smith Capital Partners Limited | Real estate | 2025 |
| Smith RUS Estates Limited | Real estate | 2017 |
| Smith System Emea Limited | Education | 2007 |
| Smithers Scenery Ltd | Arts & recreation | 2024 |
| Smokers N Vapers Limited | Wholesale & retail | 2016 |
| Smokey's Home Deli Limited | Wholesale & retail | 2023 |
| Smpa Group Ltd | Real estate | 2026 |
| Smudge Engineering Ltd | Professional & scientific | 2025 |
| Smudge Holdings Ltd | Financial services | 2025 |
| Snaapdash Limited | Information & communication | 2018 |
| SNB Partners Ltd | Administrative & support | 2017 |
| SND Medical Ltd | Professional & scientific | 2015 |
| SND Plastering Ltd | Construction | 2008 |
| SND Property Ltd | Real estate | 2019 |
| Snkrplgcy & Marketing Limited | Wholesale & retail | 2021 |
| Snow Bear Ltd | Information & communication | 2017 |
| Snow Cool REF & Air Condition Engineering Ltd | Manufacturing | 2023 |
| SNP Legal Services Limited | Professional & scientific | 2016 |
| SNZ Capital Ltd | Real estate | 2026 |
| SO Apartments (NO 1) Limited | Real estate | 2009 |
| SO Resin Ltd | Manufacturing | 2020 |
| So-G Properties Ltd | Real estate | 2018 |
| So-G Technology Ltd | Professional & scientific | 2019 |
| Sobea Ltd | Construction | 2022 |
| Sobell Rhodes Audit Limited | Professional & scientific | 2023 |
| Sobell Rhodes LLP | | 2010 |
| Sobiya Properties Ltd | Construction | 2025 |
| Sobrio Limited | Wholesale & retail | 2003 |
| Soccer International Limited | Arts & recreation | 1999 |
| Society of Friends of the Torah Limited | Health & social care | 2011 |
| Soco House Ltd | Real estate | 2022 |
| Soda and Friends Ltd | Hospitality | 2020 |
| Sofabuk Limited | Hospitality | 2023 |
| Sofsal Ltd | Real estate | 2016 |
| Softalogic Ltd | Administrative & support | 2012 |
| Software Genesis Group Limited | Information & communication | 2019 |
| SOG Manufacturing Limited | Manufacturing | 2025 |
| Soho E Consulting Ltd | Real estate | 2020 |
| Soho Music Collective Ltd | Arts & recreation | 2024 |
| SOL Property Ventures Limited | Real estate | 2022 |
| SOL Ventures Limited | Administrative & support | 2022 |
| Solar Cargo & Logistics (UK) Ltd | Transport & logistics | 2016 |
| Solevar Ltd | Real estate | 2021 |
| Solid Craft Furniture Ltd | Manufacturing | 2026 |
| Solid Facilities LLP | | 2015 |
| Solid Path Services Ltd | Professional & scientific | 2026 |
| Solton Ltd | Other services | 2018 |
| Solution Delivery Ltd | Information & communication | 2024 |
| Soléya London Ltd | Wholesale & retail | 2026 |
| Some Like IT Shot Productions Limited | Information & communication | 2007 |
| Somerbond Limited | Wholesale & retail | 1987 |
| Somerset House Management Company (RTM) Limited | Professional & scientific | 2004 |
| Sonel Services Ltd | Professional & scientific | 2012 |
| Sonex Solutions Limited | Administrative & support | 2015 |
| Soni Nitin and Sons Ltd | Health & social care | 2020 |
| Sonia Court Owners Limited | Construction | 1995 |
| Sonobex Limited | Professional & scientific | 2012 |
| Soos and Topka Ltd | Construction | 2020 |
| Sooshi Products Limited | Arts & recreation | 2017 |
| Sopher + Co LLP | | 2010 |
| Sopher Plus Limited | Financial services | 2019 |
| Sopher Taxation Limited | Professional & scientific | 2010 |
| Sopher Trustees Limited | Administrative & support | 2023 |
| Sophia Opel Plastic Surgery Ltd | Health & social care | 2023 |
| Sophia PT Limited | Real estate | 2026 |
| Sophianna's Bakery Ltd. | Hospitality | 2015 |
| Sophie & BOO LLP | | 2008 |
| Soraya Construction Ltd | Construction | 2016 |
| Sorelle Breadstall Limited | Wholesale & retail | 2019 |
| SOS Electricals and Services Limited | Construction | 2013 |
| Soul & Mind Ltd | Arts & recreation | 2022 |
| Soul Bowl Cafe Ltd | Hospitality | 2025 |
| Soul Healthcare Limited | Health & social care | 2013 |
| Soul Studio Events Limited | Hospitality | 2023 |
| Soulthreads Ltd | Other services | 2025 |
| Souly Electric Ltd | Wholesale & retail | 2025 |
| Souly Electronics Ltd | Wholesale & retail | 2025 |
| Source and Support Agency Limited | Wholesale & retail | 2014 |
| Source Managed Services Ltd | Information & communication | 2010 |
| Sourcing From China Limited | Wholesale & retail | 2025 |
| South Beach Investments Limited | Real estate | 2001 |
| South Coast Fencing and Gates Ltd | Administrative & support | 2019 |
| South East Heavy Haulage Limited | Transport & logistics | 2013 |
| South Eastern Site Management Services Limited | Professional & scientific | 2017 |
| Southam Mews Residents Company Limited | Households | 2008 |
| Southampton Car Performance Centre Ltd | Wholesale & retail | 2017 |
| Southend & City Ltd | Real estate | 2008 |
| Southern Funding Limited | Financial services | 1992 |
| Southern Group Limited | Professional & scientific | 1993 |
| Southsea (Australia) Limited | Administrative & support | 2005 |
| Southwick Village Club Limited | Hospitality | 2025 |
| Sovereign Investments (U.K.) Limited | Professional & scientific | 1990 |
| SP & Sons Construction Ltd | Construction | 2026 |
| SP Strategic Engineering Limited | Professional & scientific | 2017 |