| Seloquence Ltd | Administrative & support | 2024 |
| Seloxium Limited | Manufacturing | 2022 |
| Semantico Limited | Information & communication | 1999 |
| Sempervivum Investments Limited | Real estate | 2022 |
| SEN4N Developments Ltd | Construction | 2025 |
| SEN4N Limited | Construction | 2022 |
| Senechal Ltd | Professional & scientific | 2022 |
| Seniorpals C.I.C. | Health & social care | 2026 |
| Senli Consultancy Ltd | Financial services | 2003 |
| Sensing Space Ltd | Education | 2020 |
| Sensitlive Limited | Energy | 2008 |
| Sensyqo Ltd | Information & communication | 2021 |
| Sentinel Gateway Limited | Information & communication | 2019 |
| SEO Nigeria Ltd | Wholesale & retail | 2025 |
| Seoxha Limited | Health & social care | 2021 |
| Seracares Limited | Education | 2013 |
| Seralux Ltd | Other services | 2025 |
| Serck Limited | Extraterritorial | 1919 |
| Serck Services UK Limited | Administrative & support | 2018 |
| Serendipity Accounting Limited | Professional & scientific | 2023 |
| Serene Solutions Oxford Ltd | Wholesale & retail | 2024 |
| Sereni GYN Ltd | Health & social care | 2022 |
| Serenisima Energence Sustainable Development and Preservation Through Technology Ukeig | | 2019 |
| Serenity Lodgings Limited | Hospitality | 2026 |
| Serles Farm Cottages Management Limited | Households | 1996 |
| Serllian Ltd | Other services | 2025 |
| Serpentine Studio Ltd | Administrative & support | 2019 |
| Serv&Serv Ltd | Information & communication | 2014 |
| Service First Limited | Health & social care | 2019 |
| Service Safe Ltd | Information & communication | 2025 |
| Sesco Photography Limited | Manufacturing | 2024 |
| Sesi Food and Household Refill LLP | | 2013 |
| Sesodia Technologies Limited | Information & communication | 2025 |
| Session Types for Technology Limited | Information & communication | 2014 |
| SET in Brick and Stone Construction Ltd | Construction | 2017 |
| Setu Labs Ltd | Education | 2026 |
| Sevane Capital Limited | Financial services | 2025 |
| Seventh Hill Limited | Real estate | 2018 |
| SEVENTY5 Investments (OP) Ltd | Information & communication | 2026 |
| Seville Developments Limited | Construction | 2005 |
| SEY Blue Food Ltd | Manufacturing | 2024 |
| Seyhan Engineering Ltd | Energy | 2018 |
| Seymour Sinclair Investments Limited | Financial services | 1995 |
| Sezzac Ltd | Health & social care | 2016 |
| SFA (Oxford) Limited | Administrative & support | 2005 |
| Sfev International Ltd | Construction | 2025 |
| SFH Maintenance Limited | Construction | 2010 |
| SFZ Associates Ltd | Real estate | 2025 |
| SG Anaesthetics Limited | Health & social care | 2025 |
| SG108 Limited | Financial services | 2017 |
| SG2HC Ltd | Financial services | 2015 |
| Sgallant Ltd | Professional & scientific | 2021 |
| SGJ (Oxford) Limited | Real estate | 2013 |
| SGJ Developments Limited | Real estate | 2013 |
| SGJ Holdings Limited | Real estate | 2013 |
| SGM Dream Homes Limited | Real estate | 2026 |
| SGM Estates Limited | Real estate | 2026 |
| Sgtak Limited | Financial services | 2025 |
| SH Headington Limited | Hospitality | 2026 |
| SH. Creative Ltd. | Professional & scientific | 2005 |
| Shackletonreach Ltd | Professional & scientific | 2025 |
| Shad Shop Limited | Wholesale & retail | 2025 |
| Shafafyia Limited | Information & communication | 2019 |
| Shaheer Ltd | Hospitality | 2023 |
| Shaiek Carpet Ltd | Wholesale & retail | 2026 |
| Shaikh Transport Limited | Transport & logistics | 2024 |
| Shaikhltd Limited | Transport & logistics | 2025 |
| Shakis Ltd | Health & social care | 2016 |
| Shalbourne Close Rental Property Limited | Real estate | 2023 |
| Shalenet Limited | Construction | 2014 |
| Shamit Restaurant Limited | Hospitality | 2025 |
| Shan Shan Foods Ltd | Hospitality | 2025 |
| Shanaya Healthcare Ltd | Public administration | 2023 |
| Shaping OUR Lives National User Network Community Interest Company | Health & social care | 2002 |
| Shared Experience Limited | Arts & recreation | 1976 |
| Shari Tanaka Limited | Health & social care | 2015 |
| Shark Finesse Limited | Information & communication | 2002 |
| Sharma Group Estates Ltd | Construction | 2025 |
| Sharp Focus Productions Ltd | Information & communication | 2005 |
| Sharp Isis IP Limited | Other services | 2013 |
| Sharwety Ltd | Other services | 2025 |
| Shaun K Properties Ltd | Real estate | 2024 |
| Shavekit Ltd | Manufacturing | 2013 |
| Shaw Gibbs (Audit) Limited | Professional & scientific | 2020 |
| Shaw Gibbs Probate Limited | Financial services | 2025 |
| Shaw Gibbs Trust Corporation Limited | Other services | 2023 |
| Shaw's Carpentry and Construction Limited | Construction | 2016 |
| Shaws Corner (Salcombe) Management Limited | Real estate | 2008 |
| Shedden Hill Limited | Construction | 1990 |
| Sheermain Limited | Administrative & support | 1983 |
| Sheikh Brothers Marketing Ltd | Professional & scientific | 2016 |
| Shelma Inventories Limited | Professional & scientific | 2021 |
| Shen Day Family LLP | | 2023 |
| Shepherd and Woodward Holdings Limited | Manufacturing | 2025 |
| Shepherd Greenings Limited | Professional & scientific | 2008 |
| Sheps Cycle Shack Limited | Wholesale & retail | 2009 |
| Sheqsys.Com Ltd | Information & communication | 2016 |
| Sheriff’S Electrical Ltd | Construction | 2025 |
| Sheringham Enterprises Limited | Professional & scientific | 2006 |
| Sherman Treaters Ltd | Extraterritorial | 2019 |