| Sea BEA Transport Limited | Transport & logistics | 2003 |
| Seafield Management Company (Paignton) Limited | Households | 2005 |
| Sean Phelan Mirror Gilding Ltd | Professional & scientific | 2022 |
| Searchworthy Limited | Professional & scientific | 2018 |
| Seascape Homes Ltd | Real estate | 2015 |
| Sebadore Sports Marketing Ltd | Professional & scientific | 2018 |
| Sebano Original Ltd | Transport & logistics | 2025 |
| Sebastian Kennedy Associates Limited | Information & communication | 1997 |
| SEBDOX2 Ltd | Transport & logistics | 2022 |
| Second Echo (UK) Limited | Wholesale & retail | 2026 |
| Second State Pizza Company Limited | Hospitality | 2003 |
| Secure a Ship Limited | Administrative & support | 2011 |
| Secure a Van & Accessories Limited | Administrative & support | 2013 |
| Secure Pawz Ltd | Other services | 2021 |
| Seeneys Limited | Wholesale & retail | 2001 |
| Segritude Ltd | Information & communication | 2023 |
| Selios Group Ltd | Real estate | 2023 |
| Selldotbuy Ltd | Extraterritorial | 2022 |
| Sellon Homes Limited | Real estate | 2021 |
| Selwood Villas Ltd | Real estate | 2023 |
| Send Support Banbury Ltd | Health & social care | 2025 |
| Sendeazytransport Ltd | Transport & logistics | 2018 |
| Senhandley Limited | Professional & scientific | 2014 |
| Sensor Technology Limited | Manufacturing | 1976 |
| Sentinel 1ST Safety & Compliance Ltd | Transport & logistics | 2026 |
| Sentry Logistics Ltd | Transport & logistics | 2020 |
| Serendipity Finance Limited | Professional & scientific | 2009 |
| Sergiu Travel Limited | Administrative & support | 2022 |
| Seriously Smart Limited | Professional & scientific | 1998 |
| Services 22 Limited | Other services | 2024 |
| SET the Fire Ltd | Arts & recreation | 2025 |
| Setler House Residents Association Limited | Households | 1980 |
| Setoo AI UK Ltd | Information & communication | 2025 |
| Sevenfold Consulting Limited | Professional & scientific | 2024 |
| Sevtur Ltd | Hospitality | 2025 |
| SG Building&Decorating Ltd | Construction | 2023 |
| SG Reserve Limited | Extraterritorial | 2024 |
| SGC Engineering Ltd | Professional & scientific | 2015 |
| SGM Racepaint Limited | Administrative & support | 1997 |
| Shadow Electrical & Property Services Ltd | Construction | 2026 |
| Shafi Developments Ltd | Real estate | 2024 |
| Shah Inter Limited | Wholesale & retail | 2025 |
| Shaken & Stirred Companies Limited | Hospitality | 2023 |
| Shakespeare Tea Company Limited | Extraterritorial | 2019 |
| Shamy Original Limited | Administrative & support | 2017 |
| Shand Financial Planning Limited | Information & communication | 2016 |
| Shankin Composites Ltd | Wholesale & retail | 2026 |
| Sharkener Ltd | Manufacturing | 2026 |
| Shaun Warren Advisory Limited | Professional & scientific | 2022 |
| SHE IS Action Ltd | Information & communication | 2023 |
| Shenington Airfield Limited | Arts & recreation | 2021 |
| Shenlow Property Limited | Real estate | 2020 |
| Shepley Limited | Construction | 2005 |
| Sherer Consulting Ltd | Professional & scientific | 2025 |
| Sherin Health Care Ltd | Administrative & support | 2023 |
| Shifty Disco Limited | Information & communication | 1997 |
| Shiloh I J Ltd | Health & social care | 2018 |
| Shipston House Limited | Health & social care | 2016 |
| Shire Camping Ltd | Hospitality | 2021 |
| Shire Tyre Services Ltd | Wholesale & retail | 2012 |
| Shivay Consulting Limited | Information & communication | 2025 |
| SHM Automotive Limited | Wholesale & retail | 2017 |
| Shockware Limited | Information & communication | 2026 |
| Shoeland Trading Limited | Wholesale & retail | 2010 |
| Shop 11 Ltd | Wholesale & retail | 2023 |
| Shop Dixi Ltd | Wholesale & retail | 2013 |
| Shoregill Limited | Professional & scientific | 2013 |
| Shortalk Ltd | Professional & scientific | 2006 |
| Shotteswell Dog Walking Fields Ltd | Other services | 2026 |
| Showcase Exhibition Services Ltd. | Administrative & support | 2000 |
| Showeez Ltd | Real estate | 2019 |
| SHS Developments (Oxford) Ltd | Construction | 2020 |
| Shutterlab Ltd | Construction | 2022 |
| Shyni Exports and Imports UK Ltd | Wholesale & retail | 2024 |
| SIA HR Consultancy Ltd | Administrative & support | 2026 |
| Siam House Limited | Hospitality | 2003 |
| Sibford Manor Residents Management Company Limited | Households | 2004 |
| Sibford School | Education | 1997 |
| Sibford Trading Limited | Education | 1999 |
| Sibfordstores Ltd | Wholesale & retail | 2017 |
| Sid&Courier Ltd | Transport & logistics | 2025 |
| Siera Logistics Limited | Transport & logistics | 2024 |
| Siete Ltd | Health & social care | 2015 |
| Siewinski Limited | Construction | 2024 |
| Sight Security Services Limited | Administrative & support | 2019 |
| Sigma Panels Ltd. | Manufacturing | 2016 |
| Silbury Marketing Limited | Wholesale & retail | 1985 |
| Silesia Ltd | Transport & logistics | 2020 |
| Silman Jones Master Thatchers Ltd | Construction | 2021 |
| Silvaback Fitness Ltd | Health & social care | 2018 |
| Silver Birch Home Care Ltd | Health & social care | 2025 |
| Silver Birch Property Ltd | Real estate | 2015 |
| Silverfin Properties Ltd | Hospitality | 2026 |
| Silverprop Investments Ltd | Real estate | 2024 |
| Silvi’S Barbers Ltd | Other services | 2023 |
| SIM Surge Ltd | Information & communication | 2025 |
| Sime & Co Accountants Ltd | Professional & scientific | 2012 |
| Simiginalogistic Limited | Transport & logistics | 2020 |
| Simon Foster Photography Limited | Professional & scientific | 2004 |
| Simon House Limited | Education | 2018 |