| S-1 Group Invest Ltd | Financial services | 2024 |
| S-2 Group Invest Ltd | Financial services | 2024 |
| S-3 Group Invest Ltd | Financial services | 2024 |
| S-4 Group Invest Ltd | Financial services | 2024 |
| S-5 Group Invest Ltd | Financial services | 2024 |
| S-6 Group Invest Ltd | Financial services | 2024 |
| S-7 Group Invest Ltd | Financial services | 2024 |
| S-8 Group Invest Ltd | Financial services | 2024 |
| S-9 Group Invest Ltd | Financial services | 2024 |
| S-Group Investment Ltd | Financial services | 2021 |
| S.O'Donnell Transport Ltd | Transport & logistics | 2020 |
| S1S2S3 Limited | Professional & scientific | 2025 |
| S2S Global Branding Alliance Limited | Wholesale & retail | 2022 |
| S4BHG Limited | Financial services | 2025 |
| S@Rma Ltd | Education | 2023 |
| SA Group Construction Ltd | Construction | 2016 |
| Sabaras Limited | Professional & scientific | 2020 |
| Sabex Ltd | Information & communication | 2013 |
| Sabio MI Limited | Professional & scientific | 2015 |
| Sacx Limited | Construction | 2020 |
| Safeguarding Training & Consultancy Services Ltd | Professional & scientific | 2014 |
| Safety First Consultancy Services Ltd | Professional & scientific | 2025 |
| SAI Property Services Limited | Construction | 2002 |
| SAI Sandhya Technologies Ltd | Information & communication | 2024 |
| Saint George Hospitality Ltd | Wholesale & retail | 2015 |
| SAK Holdings Ltd | Financial services | 2023 |
| Sales & Marketing Global Limited | Information & communication | 2007 |
| Sallmanns (UK) Limited | Real estate | 1991 |
| Sally Rackham Ltd | Professional & scientific | 2019 |
| Salter and Weare Limited | Professional & scientific | 2015 |
| Salvin Associates Ltd | Professional & scientific | 2016 |
| Salwa Catering Limited | Hospitality | 2009 |
| SAM Hamer Electrical Ltd | Construction | 2021 |
| Sammani Holdings Limited | Real estate | 2018 |
| Samnixon Limited | Wholesale & retail | 2013 |
| Samovar BID Management Ltd | Professional & scientific | 2018 |
| Sampson Gate Management Company Limited | Professional & scientific | 2011 |
| Sanahasa Properties Limited | Hospitality | 2025 |
| Sanat Practice Limited | Health & social care | 2014 |
| Sanat Residential Properties Ltd | Real estate | 2017 |
| Sanctuary Films Limited | Information & communication | 2000 |
| Sandyheath Retail Limited | Wholesale & retail | 1993 |
| Sanpar Limited | Wholesale & retail | 1979 |
| Sansaar Ltd | Education | 2001 |
| Sapibla Ltd | Real estate | 2022 |
| Sapphire Learning & Development Ltd | Health & social care | 2022 |
| Sapphire Mobiles Ltd | Real estate | 2025 |
| Sarah Gagan Limited | Administrative & support | 2015 |
| Sarahaosborne Limited | Administrative & support | 2017 |
| Sarratt Community Garden CIC | Agriculture & fishing | 2022 |
| Sarratt Village C.I.C. | Wholesale & retail | 2010 |
| Sash Window Cleaning Ltd | Administrative & support | 2021 |
| SATH1 Ltd | Hospitality | 2025 |
| Satya Photography Ltd | Professional & scientific | 2023 |
| Saudi Egyptian Friendship Union UK Ltd | Education | 2016 |
| Saunders Signs Ltd | Professional & scientific | 2026 |
| Savoir Accountants Limited | Professional & scientific | 2023 |
| Savran Limited | Information & communication | 2013 |
| SBA Medical Consultancy Limited | Health & social care | 2013 |
| SBG Electrical Limited | Construction | 2023 |
| SBL Services Limited | Professional & scientific | 2021 |
| SBT Restaurant Ltd | Hospitality | 2025 |
| Scaleworks Consulting Ltd | Professional & scientific | 2026 |
| Scammell Construction Ltd | Construction | 2012 |
| Scammell Homes Ltd | Construction | 2025 |
| Scanlon Locums Limited | Professional & scientific | 2011 |
| SCM27 Consultants Limited | Professional & scientific | 2021 |
| Scotmill Agencies Ltd | Professional & scientific | 2012 |
| Scottel (ST. Albans) Limited | Real estate | 2013 |
| SCP Consulting Limited | Professional & scientific | 2012 |
| Screenclay Limited | Information & communication | 2004 |
| Scrmp Ltd | Professional & scientific | 2022 |
| Scsh Freehold Investments Limited | Households | 2020 |
| SD Medical&Health Limited | Health & social care | 2026 |
| SD Research Consulting Limited | Professional & scientific | 2024 |
| SDA Developments Limited | Construction | 2006 |
| SDL Property Ltd | Real estate | 2019 |
| Sea Salt and Mango Ltd | Manufacturing | 2023 |
| Seafield Homes Ltd | Real estate | 2024 |
| Sean Birkby Model Making Limited | Professional & scientific | 2021 |
| Sean Finnan & Associates Ltd | Professional & scientific | 2013 |
| Seapoint Investments Limited | Real estate | 2012 |
| Secret Beauty Ltd | Other services | 2025 |
| Security Air Express Limited | Transport & logistics | 1993 |
| Seemore Consulting Limited | Professional & scientific | 2016 |
| Sehgal Holding Ltd | Professional & scientific | 2012 |
| Selkie Soul Limited | Information & communication | 2020 |
| Sell UZ Limited | Hospitality | 2017 |
| Senate Bespoke Construction (Park Avenue) Ltd | Construction | 2024 |
| Sencillo Homes Ltd | Construction | 2020 |
| Senior Finance Four Limited | Professional & scientific | 2009 |
| Senior Finance Seven Limited | Professional & scientific | 2014 |
| Senior Finance SIX Limited | Professional & scientific | 2011 |
| Senior Power Products Limited | Professional & scientific | 1958 |
| Senior UK Limited | Manufacturing | 1985 |
| Seramm Ltd | Professional & scientific | 2020 |
| Serendipity Studios Ltd | Real estate | 2021 |
| Serenity Enterprises Limited | Financial services | 2020 |
| Serincourt Limited | Health & social care | 1998 |
| Serjo Limited | Real estate | 2023 |