| Scityx Limited | Information & communication | 2023 |
| Scius Communications Ltd | Administrative & support | 2015 |
| Scizen Consulting Ltd | Professional & scientific | 2026 |
| SCJ Impact Consultancy Limited | Professional & scientific | 2025 |
| SCM Portfolio Holdings | Financial services | 2024 |
| SCM22 Ltd | Professional & scientific | 2026 |
| SCO Logistic Ltd | Transport & logistics | 2019 |
| Scogor Care Ltd | Health & social care | 2025 |
| Scooby Courier Ltd | Transport & logistics | 2017 |
| Scopemargin Limited | | 1988 |
| Scopin Solutions Limited | Information & communication | 2012 |
| Scorpio DRY Cleaners Ltd | Other services | 2025 |
| Scortzy & Co Ltd | Transport & logistics | 2017 |
| Scott Jackson Independent Specialists Ltd | Wholesale & retail | 2018 |
| Scott Marine Consultants Ltd | Professional & scientific | 2020 |
| Scott Singleton Consulting Limited | Professional & scientific | 2026 |
| Scottdene Property Services Limited | Real estate | 2002 |
| Scotts FS Limited | Financial services | 2020 |
| Scotts Interiors Limited | Manufacturing | 2009 |
| Scotts Plumbing and Property Maintenance Limited | Construction | 2016 |
| Scout Digital Consulting Limited | Professional & scientific | 2026 |
| Scouting for Properties Limited | Real estate | 2019 |
| Scoutsmeout Limited | Arts & recreation | 2020 |
| Scrap App Ltd | Water & waste | 2025 |
| Scrase Partners Ltd | Other services | 2013 |
| Screen 7 Studios Ltd | Information & communication | 2026 |
| Scribbles by Steph Ltd | Arts & recreation | 2026 |
| Script This Limited | Information & communication | 2011 |
| Scriptalyst Ltd | Education | 2025 |
| Scriptmed Ltd | Professional & scientific | 2025 |
| Scripture Union | Information & communication | 1893 |
| Scrubs Lane Property Company Limited | Households | 2007 |
| Scrum and Beyond Solutions Ltd | Information & communication | 2018 |
| Scrummy Yummy Fish Ltd | Hospitality | 2023 |
| Scrypto Ltd | Information & communication | 2020 |
| Scsg Consultants Limited | Professional & scientific | 2023 |
| Scsu Ltd | Other services | 2019 |
| Scuff N Scratch Solutions Ltd | Other services | 2013 |
| Sculpt by Kelly Swann Ltd | Other services | 2021 |
| Sculthorpe Farmhouse Limited | Hospitality | 2023 |
| SD Burden Properties Ltd | Real estate | 2023 |
| SD Composites Limited | Manufacturing | 2023 |
| SD Electrical Controls Limited | Professional & scientific | 2014 |
| SD Gurney Limited | Construction | 1996 |
| SD Project Support Ltd | Professional & scientific | 2023 |
| SD Steel Services Ltd | Construction | 2025 |
| SD Tasty Foods Limited | Hospitality | 2025 |
| Sdave UK Ltd | Other services | 2019 |
| SDC Bridge Ltd | Information & communication | 2026 |
| SDD Ltd | Construction | 2024 |
| SDKR2 Ventures Limited | Real estate | 2016 |
| Sdmann Limited | Construction | 2023 |
| Sdmc Consultants Limited | Professional & scientific | 2018 |
| Sdmk Build Services Ltd | Construction | 2024 |
| SDN Communications Ltd | Information & communication | 2017 |
| Sdnd Services Ltd | Construction | 2023 |
| SDP Smart Cleaning & Logistics Limited | Administrative & support | 2020 |
| SDR ERP Consulting Ltd | Information & communication | 2022 |
| SDS Coatings Ltd | Construction | 2019 |
| SDS Food Technical Solutions Limited | Hospitality | 2026 |
| SDS Joinery Limited | Manufacturing | 2014 |
| SDT Homes Ltd | Real estate | 2024 |
| SDW Cargo Limited | Manufacturing | 2025 |
| SE Financial Trust PLC | Financial services | 2003 |
| Sea Bird Logistics Ltd | Transport & logistics | 2025 |
| Sea PVT Ltd | Real estate | 2021 |
| Sea Shepherd UK | Other services | 2023 |
| Sea-Air Logistics UK Ltd | Transport & logistics | 2026 |
| Seagull Developers Ltd | Construction | 2020 |
| Seahorse (MK) Ltd | Other services | 2023 |
| Seajay Limited | Administrative & support | 2024 |
| Seak Energy Limited | Energy | 2025 |
| Sealand Foods Limited | Wholesale & retail | 2015 |
| Seals Fodder Room Limited | Wholesale & retail | 1998 |
| Seam Consultancy Ltd | Information & communication | 2025 |
| Seam Entertainment Limited | Information & communication | 2023 |
| Seamserv Ltd | Other services | 2016 |
| Sean Rickard Limited | Administrative & support | 2011 |
| Search to Book Limited | Information & communication | 2022 |
| Searchlab Ltd | Administrative & support | 2018 |
| Searchx Limited | Administrative & support | 2025 |
| Season Inns Limited | Hospitality | 2005 |
| Seasons Caregivers Limited | Health & social care | 2020 |
| Seaton Estates Limited | Real estate | 2019 |
| Seban UK Ltd | Health & social care | 2019 |
| SEC Watchdog Limited | Information & communication | 2023 |
| Sec-It Limited | Other services | 2012 |
| Seca Services Limited | Administrative & support | 2019 |
| Secklow Asset Management Limited | Construction | 2014 |
| Secklow Consulting Ltd | Professional & scientific | 2025 |
| Seconds X OUT Limited | Manufacturing | 2014 |
| Secpen Ltd | Information & communication | 2015 |
| Secret Films Limited | Arts & recreation | 2001 |
| Secret Records Limited | Arts & recreation | 2001 |
| Section Creative Limited | Professional & scientific | 2015 |
| Secur-A-Team Ltd | Health & social care | 2024 |
| SECUR8Y Services Limited | Administrative & support | 2022 |
| Securatm Ltd | Other services | 2024 |
| Secure Tech Resourcing Ltd | Administrative & support | 2024 |
| Secured Hands Services Ltd | Wholesale & retail | 2024 |