| South Bristol (Ashton Park) Limited | Construction | 2012 |
| South Bucks Business Products Limited | Manufacturing | 1971 |
| South Bucks Fencing Ltd | Administrative & support | 2018 |
| South Bucks Hospice Development Company Limited | Construction | 2013 |
| South Bucks. Counselling | Health & social care | 2002 |
| South Eastern Machinery Services Limited | Extraterritorial | 2012 |
| South Pride Roofing Ltd | Construction | 2025 |
| South View High Wycombe Management Company Ltd | Households | 2025 |
| Southall Athletic Football Club CIC | Arts & recreation | 2022 |
| Southampton Tyres Limited | Wholesale & retail | 2018 |
| Southbourne and Desborough House Management Limited | Households | 1976 |
| Southcote Contracting Ltd | Construction | 2019 |
| Southeast Property Management Services Ltd | Households | 2022 |
| Southeast Supported Housing CIC | Health & social care | 2025 |
| Southern Construction Materials Ltd | Transport & logistics | 2025 |
| Southgate Maisonettes (27 and 28) Limited | Households | 2004 |
| Southside Datacom Ltd | Construction | 2024 |
| Souvenir Ecommerce Ltd | Wholesale & retail | 2023 |
| Sovereign Building Contractors Limited | Construction | 2000 |
| Sovereign Capital Wealth Limited | Real estate | 2010 |
| Sovereign Property Management Ltd | Real estate | 2022 |
| Sowow Ltd | Manufacturing | 2018 |
| Soyee Foods Limited | Hospitality | 2009 |
| SP Energy Assessors LLP | | 2025 |
| Spa-Licious Ltd | Other services | 2015 |
| Space Ravers Ltd | Hospitality | 2023 |
| Space Staffing Limited | Hospitality | 2016 |
| Space Working Limited | Professional & scientific | 2025 |
| Spacedab Properties Limited | Real estate | 2020 |
| Spaceman Innovations Limited | Administrative & support | 2015 |
| Spacers Contract Tiling Limited | Construction | 2008 |
| Spad Holdings Limited | Professional & scientific | 2005 |
| Spang Group Limited | Professional & scientific | 2016 |
| Spanning Solutions Ltd | Information & communication | 2012 |
| Spanton 199 Ltd | Real estate | 2026 |
| Sparc Intelligence Limited | Information & communication | 2023 |
| Sparkes London Limited | Professional & scientific | 2020 |
| Sparkles Party Pieces Ltd | Arts & recreation | 2024 |
| Sparkling Car Wash Ltd | Administrative & support | 2025 |
| Sparks Cafe Limited | Hospitality | 2020 |
| Sparta Solutions Limited | Information & communication | 2022 |
| SPB Marlow Limited | Administrative & support | 2017 |
| Speakman Gardens Residents Association Limited | Extraterritorial | 2008 |
| Spearbuild Ltd | Construction | 2025 |
| Special Air Systems Ltd | Construction | 2010 |
| Special Car Wash Ltd | Other services | 2017 |
| Specialised Windscreens Ltd | Wholesale & retail | 2012 |
| Specialist Cable Supplies Limited | Wholesale & retail | 2011 |
| Specialist Cardiac Services Limited | Health & social care | 2026 |
| Specialist Screeding Ltd | Construction | 2019 |
| Speck Pumps (UK) Limited | Manufacturing | 1984 |
| Spectrum Hose Limited | Manufacturing | 1982 |
| Specvital Limited | Wholesale & retail | 1988 |
| Speech and Language Therapy Services Ltd. | Health & social care | 2006 |
| Speedline Taxis (HW) Ltd | Transport & logistics | 2018 |
| Speedmixer Ltd | Professional & scientific | 2020 |
| Speedrops Logistics Ltd | Transport & logistics | 2026 |
| Speedy Iron Limited | Other services | 2003 |
| Spencer and Gray Ltd | Wholesale & retail | 2025 |
| Speqeez Ltd | Wholesale & retail | 2026 |
| Spice Garden Limited | Hospitality | 2024 |
| Spice Lounge Wycombe Limited | Hospitality | 2026 |
| Spice of High Wycombe Ltd | Hospitality | 2016 |
| Spicy Rasoi Limited | Wholesale & retail | 2026 |
| Spicy Tasty Pizza Limited | Hospitality | 2024 |
| Spiffy Stores Limited | Wholesale & retail | 2021 |
| Spinks & Denning Limited | Extraterritorial | 1946 |
| Spinks Lettings Limited | Real estate | 2025 |
| Spira Design Ltd | Professional & scientific | 2025 |
| Spira U.K. Limited | Manufacturing | 1989 |
| Spire Sound Ltd | Information & communication | 2024 |
| Spirit of the Rainbow Limited | Wholesale & retail | 2023 |
| SPJ Contracting Ltd | Construction | 2019 |
| SPJ Management Services Ltd | Real estate | 2020 |
| SPJ Plant Ltd | Other services | 2021 |
| SPJ Real Estate Ltd | Real estate | 2021 |
| Splash Monsters Ltd | Education | 2023 |
| Splash Sensory Ltd | Education | 2025 |
| Spoolex Limited | Wholesale & retail | 2012 |
| Sporting Chance Limited | Administrative & support | 2025 |
| Sporting Ventures International Ltd | Administrative & support | 2020 |
| Sports and Swim Stars Ltd | Education | 2020 |
| Sports Memorabilia Store Limited | Manufacturing | 2025 |
| Sports Motion Limited | Information & communication | 2025 |
| Spot Design Ltd | Information & communication | 2012 |
| Spot on Digital Imaging Limited | Manufacturing | 1988 |
| Spot on Print Limited | Manufacturing | 2017 |
| SPP Transport Ltd | Transport & logistics | 2002 |
| SPR Cars Limited | Transport & logistics | 2025 |
| Spreadalicious Ltd | Manufacturing | 2025 |
| Sprigs Investment Private Limited | Real estate | 2022 |
| Springbok Electrical Ltd | Construction | 2017 |
| Springwater Mill Management Company Limited | Administrative & support | 1988 |
| Sprint Security Ltd | Construction | 2006 |
| Sprinters Travel Ltd | Transport & logistics | 2015 |
| Sprk Electrical Ltd | Construction | 2018 |
| Sprowts Ltd | Wholesale & retail | 2018 |
| SPS Technology Holdings Ltd | Professional & scientific | 2019 |
| SPS Technology Limited | Administrative & support | 2017 |
| Spur Electrical Ltd | Construction | 2020 |