| Saints FC Ltd | Arts & recreation | 2025 |
| Sallis Truckwash Ltd | Transport & logistics | 2025 |
| SAM Archer Limited | Information & communication | 2011 |
| SAM Cornall Ltd. | Real estate | 2002 |
| Sandy Powder Coating Limited | Manufacturing | 1994 |
| Sandy Semiconductor Test Solutions Limited | Manufacturing | 2026 |
| Sapori DI Italia Ltd | Hospitality | 2025 |
| Saragusta Spirits Co. Ltd | Manufacturing | 2020 |
| Sarah Morgan Consulting Limited | Professional & scientific | 2022 |
| Sasandra Ltd | Other services | 2023 |
| Sash Student Accommodation Developments Limited | Construction | 2026 |
| Satoshi Nakamoto | Administrative & support | 2018 |
| Savi (Steve's Audio Visual Installations) Limited | Professional & scientific | 2014 |
| Savon DE Terre Ltd | Manufacturing | 2026 |
| Saward Saab Limited | Wholesale & retail | 1998 |
| Sayes Mentoring Ltd | Administrative & support | 2008 |
| Sb.Autodetailing Ltd | Administrative & support | 2023 |
| Sccs Survey Equipment Limited | Wholesale & retail | 2005 |
| Scenic Escape Limited | Manufacturing | 2024 |
| Scentience Original Ltd | Manufacturing | 2025 |
| Scindeco Property Ltd | Real estate | 2026 |
| Scoot Auto Logistics Ltd | Transport & logistics | 2018 |
| Scope Link Staffing Limited | Administrative & support | 2025 |
| Scorelift Ltd | Information & communication | 2022 |
| Sealed Air (Witham) Limited | Wholesale & retail | 1982 |
| Sealed Air Holdings UK I Limited | Professional & scientific | 2020 |
| Sealed Air Holdings UK II Limited | Financial services | 2026 |
| Sealed Air Holdings UK III Limited | Financial services | 2026 |
| Sealed Air Holdings UK Limited | Financial services | 2020 |
| Sealed Air IP Limited | Financial services | 2024 |
| Sealed Air Limited | Manufacturing | 1997 |
| Sealed Air Trustee Limited | Financial services | 2002 |
| Sealed Air UK Limited Partnership | | 2020 |
| Seamless Building Ltd | Construction | 2024 |
| Secret Beverage Company Limited | Hospitality | 2023 |
| Secure Automotive Support Ltd | Wholesale & retail | 2018 |
| Secure Business Advice Ltd | Financial services | 2006 |
| Secure Group Holdings Limited | Financial services | 2016 |
| Secure Technologies Ltd | Information & communication | 2010 |
| Security and Development Services Limited | Other services | 2025 |
| Seen Clean Ltd | Administrative & support | 2002 |
| SEH Property Development Ltd | Real estate | 2024 |
| Select Installations Ltd | Construction | 2018 |
| Sell New Ltd | Real estate | 2014 |
| Send & Health Support Ltd | Education | 2024 |
| Senkussales Ltd | Wholesale & retail | 2026 |
| Sense of Story Ltd | Professional & scientific | 2020 |
| Senta Wellness Limited | Other services | 2022 |
| Sentinai Ltd. | Information & communication | 2026 |
| Serious About IT Limited | Information & communication | 2004 |
| Serkiova Consulting Ltd | Administrative & support | 2016 |
| Setting OUT Surveys Ltd | Construction | 2017 |
| Seventy Three Property Ltd | Real estate | 2025 |
| SF Design Consultants Limited | Professional & scientific | 2012 |
| SG Autos Ltd | Wholesale & retail | 2023 |
| SGW Consultancy Limited | Administrative & support | 2010 |
| Shane Allsop Landscaping Limited | Administrative & support | 2019 |
| Shane Hawkes Window Cleaning Limited | Administrative & support | 2018 |
| Shangani House Ltd | Real estate | 2019 |
| Shannon Motors Limited | Wholesale & retail | 2013 |
| Shelan Communications Limited | Construction | 2001 |
| Shiker Consulting Ltd. | Information & communication | 2011 |
| Shineblade Ltd | Manufacturing | 2024 |
| Show Video Ltd | Information & communication | 2026 |
| Shume Bottle Emporium Limited | Wholesale & retail | 2018 |
| SI FFF Coaching LLP | | 2025 |
| Sibe Investments Ltd | Real estate | 2022 |
| Signal One Safe Ltd | Information & communication | 2026 |
| Signature Homes Estate Agents Limited | Financial services | 2024 |
| Signature Recruitment Solutions Ltd | Administrative & support | 2022 |
| Silly Puffin Limited | Administrative & support | 2023 |
| Silver Lining Foundation | Health & social care | 2020 |
| Silvertone Cleaning Company Limited | Administrative & support | 2002 |
| Simba Hosting Limited | Administrative & support | 2019 |
| Simba IT Services Limited | Information & communication | 2017 |
| Simon Bradbury Estate Agency Services Ltd | Professional & scientific | 2024 |
| Simon David Bathrooms Limited | Construction | 2019 |
| Simon Priestley (2025) Limited | Professional & scientific | 2025 |
| Sion Consultancy Ltd | Other services | 2019 |
| Sirius-S Ltd | Administrative & support | 2025 |
| SIX Paths Software Ltd | Information & communication | 2019 |
| SJ Knowles IT Limited | Information & communication | 2013 |
| Sjbpractice Ltd | Administrative & support | 2017 |
| SJC Suction Ltd | Construction | 2025 |
| SJI Management Ltd | Hospitality | 2025 |
| Skincredible Ltd | Other services | 2025 |
| Skydio Ltd | Health & social care | 2022 |
| SLH Installations Limited | Construction | 2025 |
| Smart Consumer Alliance Limited | Other services | 2017 |
| Smart Logistics Solutions Limited | Transport & logistics | 2012 |
| Smart Niche Products Limited | Professional & scientific | 2022 |
| Smart Room Systems Limited | Extraterritorial | 2005 |
| Smartbrg Limited | Education | 2023 |
| Smartech Management Ltd | Administrative & support | 2018 |
| Smharmes Ltd | Construction | 2014 |
| Smith and Company (Demolition) Limited | Wholesale & retail | 1978 |
| Smith Brothers Property Co Limited | Real estate | 2025 |
| Smith-Bourne Ltd | Real estate | 2019 |
| Smithandco Ltd | Real estate | 2020 |
| Smithpack Limited | Manufacturing | 1984 |