| S3R Ltd | Real estate | 2019 |
| S6 Developments Limited | Construction | 2025 |
| SA 2001 Holdings Ltd | Financial services | 2019 |
| SA Accounts on Time Limited | Professional & scientific | 2024 |
| SA Costume Design Ltd | Information & communication | 2018 |
| SA Electrics and Renovations Ltd | Construction | 2023 |
| SA Global Accounting Services Limited | Professional & scientific | 2024 |
| SA Global Trading Hub Limited | Wholesale & retail | 2025 |
| SA Histopathologists Limited | Health & social care | 2018 |
| Saachi Medicare Ltd | Health & social care | 2022 |
| Saarj Limited | Wholesale & retail | 2019 |
| Saas Sourcing Limited | Information & communication | 2011 |
| Saas-Enta Ltd | Information & communication | 2026 |
| Sabaluxgroup Ltd | Construction | 2022 |
| Sabre Dies Limited | Manufacturing | 1992 |
| Sabre Financial Solutions Limited | Information & communication | 2009 |
| Sachin Enterprises Ltd | Wholesale & retail | 2016 |
| Sacp Properties Limited | Administrative & support | 2011 |
| Sacre Associates LLP | | 2006 |
| Sadie Loves Tuition Limited | Education | 2025 |
| Sadler Fabrications Ltd | Manufacturing | 2024 |
| Safcalligraphy Ltd | Wholesale & retail | 2020 |
| Safe and Sound Essex Limited | Wholesale & retail | 2010 |
| Safe and Sound Trade Limited | Wholesale & retail | 2025 |
| Safe Technologia Limited | Information & communication | 2023 |
| Safe Voyages Limited | Information & communication | 2013 |
| Safedrive Ltd | Education | 2026 |
| Safeguard Cyber Security Ltd | Information & communication | 2014 |
| Safeserv Ltd | Information & communication | 2023 |
| Safety Signs UK Ltd | Wholesale & retail | 2006 |
| Safetynet (Herts) Limited | Information & communication | 2018 |
| Saffron Environmental Limited | Construction | 2008 |
| Saffron Grill Woodham Ltd | Hospitality | 2025 |
| Saffy Sweets Limited | Wholesale & retail | 2025 |
| Safl Property Ltd | Real estate | 2017 |
| SAFL10 Ltd | Real estate | 2022 |
| SAI Digidata Limited | Information & communication | 2023 |
| SAI RIA Homes Ltd | Real estate | 2023 |
| Saich Communications Ltd | Information & communication | 2015 |
| Saigon LUX Ltd | Wholesale & retail | 2024 |
| Saint Hyacinth Healthcare Limited | Administrative & support | 2021 |
| Sait Services Ltd | Information & communication | 2025 |
| Sakura House Massage Limited | Health & social care | 2023 |
| Salamiboye Limited | Real estate | 2016 |
| Salamtech Limited | Information & communication | 2010 |
| Salco Precision Engineering Limited | Manufacturing | 2003 |
| Salcombe Gardens Management Company Limited | Households | 1998 |
| Salemdii Tekh Limited | Other services | 2022 |
| Sales Smart Ltd | Information & communication | 2013 |
| Sales Vision Ltd | Professional & scientific | 2024 |
| Salman & Brothers Ltd | Wholesale & retail | 2026 |
| Salmar Properties Limited | Construction | 2017 |
| Salmon Parade Investments Ltd | Real estate | 2015 |
| Salon 9 Limited | Other services | 2015 |
| Salsatapas Ltd | Hospitality | 2024 |
| Saltcoate Trade Windows Limited | Manufacturing | 2008 |
| Saltlight City Ltd | Information & communication | 2025 |
| Saltmarsh Developments Limited | Construction | 2020 |
| Saltmarsh One Limited | Households | 2024 |
| Salty Sugar Limited | Professional & scientific | 2012 |
| Salud & Co Ltd | Hospitality | 2025 |
| Salvation Army General Insurance Corporation Limited(The) | Financial services | 1909 |
| SAM Church Investments Limited | Professional & scientific | 2017 |
| SAM Cruz Limited | Arts & recreation | 2020 |
| SAM Lewis Landscapes & Gardens Ltd | Administrative & support | 2021 |
| SAM Peek Consultancy Ltd | Information & communication | 2018 |
| SAM Sidney Ltd | Professional & scientific | 2024 |
| SAM Slack Fitness Ltd | Arts & recreation | 2024 |
| SAM Taylor Professional Decorating Ltd | Construction | 2024 |
| Samadhi Tutors Ltd | Education | 2024 |
| Saman Widyaratne Legal Ltd | Other services | 2020 |
| Samaz Workforce Ltd | Hospitality | 2019 |
| Same Day Handyman Ltd | Construction | 2021 |
| Samient Financial Limited | Professional & scientific | 2016 |
| Sammeg Ltd | Real estate | 2019 |
| Sampson K9 Products Ltd | Agriculture & fishing | 2021 |
| Samsat Satellite Ltd | Information & communication | 2019 |
| Samscope Ltd | Construction | 2005 |
| Samster Limited | Hospitality | 2018 |
| Samurai Airsoft Ltd | Wholesale & retail | 2024 |
| Sanctuary Letting Ltd | Real estate | 2020 |
| Sandford Clothing Ltd | Wholesale & retail | 2025 |
| Sandon Brook Residents Limited | Professional & scientific | 2003 |
| Sandweb Ltd | Professional & scientific | 2018 |
| Sanechoice Limited | Information & communication | 2004 |
| Saneycare Services Ltd | Health & social care | 2025 |
| Sanford Motors Limited | Wholesale & retail | 2015 |
| Sanguine Sports Ltd | Wholesale & retail | 2012 |
| Sankara Solutions Limited | Administrative & support | 2023 |
| Sanman Living & Co Ltd | Households | 2025 |
| Sannidhi Limited | Real estate | 2020 |
| Sanrose Investments Limited | Extraterritorial | 2012 |
| Sant Lucijaa Ltd | Wholesale & retail | 2017 |
| Santio Limited | Hospitality | 2018 |
| Santraxco Limited | Wholesale & retail | 2021 |
| Sanverdi Limited | Wholesale & retail | 2015 |
| Sanyou International (UK) Ltd | Wholesale & retail | 2024 |
| Saphore LLP | | 2013 |
| Sappal Brothers Property Ltd | Real estate | 2025 |
| Sappal Properties Limited | Real estate | 2020 |