| South East Audio Limited | Wholesale & retail | 2026 |
| South Fire Protection Ltd | Construction | 2020 |
| South Light Ltd | Real estate | 2021 |
| South London Resource Centre for Visually Impaired People | Health & social care | 2002 |
| South West Dental Clinics Limited | Health & social care | 2014 |
| South WLC Limited | Wholesale & retail | 1993 |
| Southampton Stay With ME Ltd | Hospitality | 2024 |
| Southeastmoe Ltd | Wholesale & retail | 2023 |
| Southern Coach Lines Ltd. | Transport & logistics | 2018 |
| Southern Communications EBT Newco Limited | Information & communication | 2018 |
| Southern Communications Networks Limited | Information & communication | 2009 |
| Southern Fire & Maintenance Ltd | Administrative & support | 2023 |
| Southern Mobility Services Ltd | Health & social care | 1997 |
| Southern NDT Services Ltd | Professional & scientific | 2022 |
| Southern Roofline Supplies Limited | Construction | 2013 |
| Southern Trailers Limited | Wholesale & retail | 2008 |
| Southfields EP Access Road Ltd | Real estate | 2024 |
| Sovereign Advances Limited | Financial services | 2009 |
| Sovereign BDW (Hutton Close) LLP | | 2016 |
| Sovereign BDW (Newbury) LLP | | 2013 |
| Sovereign Car Sales Limited | Wholesale & retail | 2012 |
| Sovereign Hill Partnership LLP | | 2023 |
| Sovereign Housing Capital PLC | Financial services | 2009 |
| Sovereign Housing Design and Build Limited | Construction | 2007 |
| Sovereign Housing Developments Limited | Construction | 2010 |
| Sovereign Housing Partnerships Limited | Construction | 2010 |
| Sovereign Housing Property Services Limited | Administrative & support | 2013 |
| Sovereign Land & Property Ltd. | Real estate | 2017 |
| Sovereign Maintenance Limited | Extraterritorial | 2016 |
| Sovereign Property Care Limited | Extraterritorial | 2016 |
| Space AGE Films Limited | Information & communication | 2009 |
| SPACE2ENJOY Limited | Hospitality | 2021 |
| SPACE2PROSPER Limited | Real estate | 2007 |
| Spacewalker Consulting Ltd | Professional & scientific | 2025 |
| Spafax International Holdings Limited | Financial services | 2018 |
| Spafax International Limited | Other services | 1979 |
| Spangles Events Limited | Administrative & support | 2025 |
| Spark Projects and Development Ltd | Construction | 2023 |
| Sparky SYD Electrical Ltd | Construction | 2021 |
| SPC Training & Consultancy Limited | Education | 2019 |
| Spearhead Computing Limited | Information & communication | 1999 |
| Specific Marketing.Co.Uk Limited | Information & communication | 2010 |
| Spectraforge Ltd | Information & communication | 2025 |
| Spectrum Premier Homes Limited | Construction | 1994 |
| Speedicare Limited | Health & social care | 2024 |
| Speedy Windows (South) Limited | Construction | 2022 |
| Spencer & Peyton Ltd | Other services | 2009 |
| Spenny Holdings Limited | Financial services | 2021 |
| Speranza Investment Inc Ltd | Construction | 2012 |
| Sphere Enterprises Ltd | Real estate | 2022 |
| Spice Route Takeaway Limited | Hospitality | 2025 |
| Spicy Tadka Staines Limited | Hospitality | 2025 |
| Spillers Limited | Financial services | 1887 |
| Spillers Overseas Limited | Financial services | 1901 |
| Spine Health Centre Ltd | Health & social care | 2023 |
| Spirepath Limited | Information & communication | 2005 |
| Spires Media Ltd | Information & communication | 2025 |
| Spirit and Thread Ltd | Wholesale & retail | 2025 |
| Spiritus Technical Services Ltd | Construction | 2018 |
| Splendour Consultancy Ltd | Information & communication | 2017 |
| Sporting Edge (UK) Limited | Professional & scientific | 2005 |
| Sportiq Consulting Ltd | Professional & scientific | 2025 |
| Sports Baba Ltd | Information & communication | 2020 |
| Spotlesspro Cleaning-Ironing Services Ltd | Administrative & support | 2025 |
| Spotlight Publishing Limited | Information & communication | 2011 |
| Spots-Physio Ltd | Health & social care | 2024 |
| Spraggs Medical Services Ltd | Health & social care | 2022 |
| Spring Grove Services Group Limited | Professional & scientific | 1910 |
| Springdove Ltd | Health & social care | 2014 |
| Springfield Park Care Home Limited | Health & social care | 2017 |
| Springrise Ltd | Hospitality | 2026 |
| Springvista Limited | Professional & scientific | 2003 |
| Sprinkler Training Solutions Ltd | Education | 2024 |
| Sprint FIX Limited | Wholesale & retail | 2013 |
| SPW Project Management Ltd | Professional & scientific | 2021 |
| Square & Compass Building Supplies Ltd | Wholesale & retail | 2021 |
| Square and Compass Sewage Treatment Services Ltd | Water & waste | 2025 |
| Square Marbles Limited | Extraterritorial | 2015 |
| Squaring Red Ltd | Real estate | 2024 |
| Squirrel Wood Partners LLP | | 2024 |
| Squirrels Corner Development Ltd | Construction | 2025 |
| SR Accountancy Limited | Professional & scientific | 2012 |
| SR Advanced Practitioner Ltd. | Information & communication | 2021 |
| SR Domestic Electrical Services Limited | Construction | 2025 |
| Srdp Property Ltd | Real estate | 2026 |
| Sree Balaji Limited | Wholesale & retail | 2024 |
| SRF (Intergrated Communications) Ltd | Professional & scientific | 2002 |
| SRI Vasavi Estates Ltd | Real estate | 2023 |
| SRK Colden Limited | Health & social care | 2015 |
| SRK Portfolio Limited | Real estate | 2021 |
| SRM IT Consulting Limited | Information & communication | 2018 |
| Srvs and Partners Limited | Information & communication | 2017 |
| SSA IT Solutions Limited | Information & communication | 2024 |
| SSM13 Ltd | Transport & logistics | 2024 |
| ST James Electrical Services Limited | Construction | 2014 |
| ST James Place Freehold Ltd | Real estate | 2025 |
| ST James Residence Ltd | Real estate | 2017 |
| ST London Ltd | Real estate | 2024 |
| ST Michael's Hospice (North Hampshire) | Health & social care | 1991 |
| ST Michael's Hospice (North Hampshire) Trading Limited | Wholesale & retail | 2026 |