| Saphisle Limited | Information & communication | 2018 |
| Saptami Ltd | Information & communication | 2019 |
| Sara J Ltd. | Administrative & support | 2006 |
| Sara Land Ltd | Real estate | 2022 |
| Sarah Blackah Publishing Ltd | Wholesale & retail | 2021 |
| Sarah Lawrence Studio Ltd | Arts & recreation | 2019 |
| Sarah Smith PA Ltd | Other services | 2025 |
| Sarmayacar Ltd | Information & communication | 2017 |
| Sarner International Limited | Professional & scientific | 1988 |
| Sarner Limited | Construction | 2014 |
| SAS & SS LLP | | 2023 |
| Sate Hand Car Wash Ltd | Administrative & support | 2024 |
| Satellite Assured Limited | Extraterritorial | 2011 |
| Satellite Assured Services Holdings Ltd | Financial services | 2022 |
| Satellite Assured Services Limited | Other services | 2009 |
| Satoru Training UK Limited | Administrative & support | 2020 |
| Saubell Limited | Professional & scientific | 1969 |
| Save the World Club | Water & waste | 2002 |
| Save Thorpeness Limited | Other services | 2026 |
| Sawwing Limited | Administrative & support | 2022 |
| SAZ Ltd | Hospitality | 2026 |
| Sazerac Innovative Spirits UK Ltd | Wholesale & retail | 2024 |
| Sazerac UK Limited | Wholesale & retail | 2003 |
| SB Vending Limited | Wholesale & retail | 2023 |
| SBA Logistics Ltd | Wholesale & retail | 2023 |
| Sbdb Consulting Ltd | Professional & scientific | 2025 |
| SC Recruitment Ltd | Administrative & support | 2025 |
| Scai Project Management Ltd | Professional & scientific | 2025 |
| Scarramouche Consulting Limited | Professional & scientific | 2023 |
| Scenespace Studios Ltd | Information & communication | 2025 |
| Scholasta Limited | Administrative & support | 2013 |
| Schwarzenegger Limited | Information & communication | 2023 |
| Scientia Capital Management Ltd | Extraterritorial | 2025 |
| Scomshell Ltd | Information & communication | 2011 |
| Scotsway Ltd | Wholesale & retail | 2020 |
| Scottish Trust Managers Limited | Real estate | 1936 |
| Scotts Fish & Chips Limited | Hospitality | 2008 |
| Screetech Cosy Ltd | Wholesale & retail | 2025 |
| SD Film Productions Limited | Information & communication | 2023 |
| SD Power Systems Consulting Limited | Professional & scientific | 2022 |
| SDE Compliance Limited | Professional & scientific | 2024 |
| SDG Investment Group Ltd | Financial services | 2022 |
| SDG Knowledge Limited | Information & communication | 2004 |
| SDG New Media Ltd | Professional & scientific | 2006 |
| Sdjg Management Limited | Professional & scientific | 2017 |
| SDP Ventures Ltd | Other services | 2019 |
| Sea Global Ltd | Wholesale & retail | 2022 |
| Sea View CT6 Ltd | Real estate | 2017 |
| Seaborne Communications Ltd | Professional & scientific | 2015 |
| Sealgair Management Limited | Real estate | 2022 |
| Sean Haven Properties Ltd | Real estate | 2021 |
| Seapoint Finance UK Investments Limited | Information & communication | 2025 |
| Seapoint Finance UK Limited | Information & communication | 2024 |
| Searchai Solutions Ltd | Information & communication | 2026 |
| Seashell Films Ltd | Information & communication | 2026 |
| Seasnl Ltd | Professional & scientific | 2023 |
| SEASON1 Catering Ltd | Hospitality | 2017 |
| SEB Mclauchlan Limited | Administrative & support | 2019 |
| Second of July Strike OFF Limited | Households | 2026 |
| Securefix Ltd | Wholesale & retail | 2026 |
| Security for Expenses Ltd | Financial services | 2016 |
| Seedis House Ltd | Wholesale & retail | 2025 |
| Sefton Lodge Freeholders Limited | Households | 2019 |
| SEL Business Solutions Limited | Professional & scientific | 2006 |
| Selaj Properties Ltd | Real estate | 2024 |
| Seldi Service Ltd | Professional & scientific | 2007 |
| Seldoc Healthcare Ltd | Health & social care | 2014 |
| Select & PAY (London) Ltd | Other services | 2016 |
| Selina Business Services Limited | Information & communication | 2015 |
| Sellerspring Limited | Professional & scientific | 2025 |
| Selliah & Kana Properties Ltd | Real estate | 2023 |
| Selling and Buying Limited | Wholesale & retail | 2018 |
| Sellmed Ltd | Administrative & support | 2024 |
| Selt Limited | Professional & scientific | 2024 |
| Sena Enterprise Ltd | Construction | 2019 |
| Sentinel Watch Company Limited | Manufacturing | 2024 |
| Sentpoint Properties Limited | Real estate | 2003 |
| Seon Vision Ltd | Health & social care | 2025 |
| Seoul Motors Ltd. | Wholesale & retail | 2005 |
| Sepia Labs Ltd | Professional & scientific | 2023 |
| Seramontt Limited | Wholesale & retail | 2014 |
| Serene Stays Yorkshire Limited | Real estate | 2024 |
| Serenity Recovery Centre Ltd | Health & social care | 2025 |
| Sergi Medical Ltd | Professional & scientific | 2022 |
| Seribus Compliance Ltd | Professional & scientific | 2020 |
| Serica (UK) Co. Ltd | Wholesale & retail | 2014 |
| Serve UK Technologies Ltd. | Energy | 2016 |
| Sesame Design Limited | Professional & scientific | 2003 |
| Seven Days Away Limited | Real estate | 2015 |
| Seven Icons Limited | Administrative & support | 2019 |
| Seven Sky Logistics Europe Limited | Wholesale & retail | 2020 |
| Seven Vasils Ltd | Construction | 2025 |
| Seventy Seven Invest Ltd | Financial services | 2013 |
| Severn Court (Kingston) Freehold Limited | Households | 2009 |
| Sevii Associates Limited | Construction | 2022 |
| Sevii Group Limited | Information & communication | 2025 |
| Sexton Barber Ltd | Other services | 2025 |
| Seyg Ltd | Hospitality | 2020 |
| Seymour Lodge (Hampton Wick) Residents Association Limited | Households | 1965 |
| Sfeb Limited | Real estate | 2024 |