| Silt (UK) Limited | Professional & scientific | 1997 |
| Silver Lining Interactive Ltd | Information & communication | 2024 |
| Silver Linings Collection Limited | Real estate | 2026 |
| Silver Linings Property Group UK Limited | Financial services | 2026 |
| Silver Linings Real Estate Limited | Real estate | 2026 |
| Silver Linings Stays Limited | Real estate | 2026 |
| Silverstone MCR Ltd | Other services | 2026 |
| Silvertown Taxis Ltd | Transport & logistics | 2019 |
| Silvertown Taxis Macclesfield Ltd | Transport & logistics | 2019 |
| Simarch Limited | Construction | 1994 |
| Simon Alexander Construction Ltd | Construction | 2024 |
| Simon Brassington Consulting Ltd | Information & communication | 2025 |
| Simon Frith Upholstery Limited | Manufacturing | 2018 |
| Simon Longden Ltd | Construction | 2015 |
| Simon Webb Limited | Manufacturing | 2008 |
| Simon Wilkinson Flooring Specialist Limited | Wholesale & retail | 2023 |
| Simons Trusted Companions Ltd | Other services | 2026 |
| Simple Financial Advice Limited | Financial services | 2006 |
| Simple Solutions Group Ltd | Administrative & support | 2026 |
| Simplicity Granite Ltd | Manufacturing | 2008 |
| Simplified IT Services Limited | Information & communication | 2015 |
| Simplified Property Ltd | Real estate | 2024 |
| Simply Beds and Mattresses Ltd | Wholesale & retail | 2023 |
| Simply Bliss Nails and Beauty Limited | Other services | 2020 |
| Simply Home Collection Ltd | Extraterritorial | 2023 |
| Simply Property Developments LLP | | 2010 |
| Simply Travel Brokers Limited | Administrative & support | 2014 |
| Simplyone Ashton Limited | Health & social care | 2021 |
| Simplyone Droylsden Limited | Health & social care | 2021 |
| Simpson Holland Ltd | Professional & scientific | 2024 |
| Sinead Kavanagh Ltd | Other services | 2017 |
| Singleton Bespoke Joinery Limited | Construction | 2021 |
| Sisolco Ltd | Information & communication | 2026 |
| SIX Hats Ltd | Information & communication | 2021 |
| Sixfour Consulting Limited | Professional & scientific | 2014 |
| Sizeable Limited | Professional & scientific | 2020 |
| Sizzor Sisters Limited | Real estate | 1999 |
| SJC Fabrication Limited | Manufacturing | 2011 |
| SJC Professional Services Limited | Administrative & support | 2016 |
| SJD Free Solar (UK) 2 Ltd | Energy | 2013 |
| SJD Free Solar (UK) 3 Ltd | Energy | 2013 |
| SJG Bars Ltd | Hospitality | 2026 |
| SJS Livery Limited | Agriculture & fishing | 2024 |
| SJW Residential Limited | Hospitality | 2024 |
| SK Collects Ltd | Arts & recreation | 2025 |
| SK Foods N Beverages Ltd | Hospitality | 2026 |
| SK Kindred Limited | Professional & scientific | 2007 |
| SK Landscaping & Drainage Ltd | Administrative & support | 2025 |
| SK Respite CIC | Health & social care | 2026 |
| SK10 Consulting Limited | Professional & scientific | 2017 |
| SK10 Limited | Real estate | 2023 |
| SK11 Fastfood Ltd | Hospitality | 2026 |
| SKA Organisation | Professional & scientific | 2011 |
| Ski-Easy Limited | Professional & scientific | 2003 |
| SKILLS4U Ltd | Wholesale & retail | 2022 |
| Skout Public Relations Ltd | Professional & scientific | 2010 |
| Skout Trustees Limited | Administrative & support | 2023 |
| Skye Outdoor Living Ltd | Construction | 2022 |
| Skyline House Ltd | Hospitality | 2026 |
| Skyward Visuals Ltd | Construction | 2020 |
| Slack Street Garage & MOT Centre Limited | Wholesale & retail | 2017 |
| SLB Homes Ltd | Real estate | 2025 |
| SLD Solutions Limited | Professional & scientific | 2009 |
| Sleath Distributions Ltd | Wholesale & retail | 2025 |
| Sleep and Go Limited | Hospitality | 2025 |
| Sleep Master Europe Limited | Wholesale & retail | 2014 |
| SLG Plastering & Home Improvements Ltd | Construction | 2024 |
| SLH Training & Nutrition Limited | Other services | 2021 |
| Slice of PIE Designs Limited | Arts & recreation | 2016 |
| Slick and Slide Suspension Servicing Ltd | Manufacturing | 2015 |
| Slonee Ltd | Wholesale & retail | 2022 |
| SM HSE Management Ltd | Construction | 2025 |
| SM Surv Limited | Construction | 2015 |
| Smart Analytics Holdings Limited | Information & communication | 2005 |
| Smart Analytics Limited | Information & communication | 2000 |
| Smart Document Solutions Limited | Information & communication | 2006 |
| Smart Fleet Media Limited | Information & communication | 2015 |
| Smarternomics Limited | Information & communication | 2014 |
| Smartflush Ltd | Manufacturing | 2003 |
| SME Creations & Design Limited | Extraterritorial | 2021 |
| Smile Anyway Limited | Wholesale & retail | 2026 |
| Smith Risk Management Limited | Professional & scientific | 2021 |
| Smith's Dairies Limited | Wholesale & retail | 2011 |
| Smithy Court (Marple) RTM Company Limited | Households | 2021 |
| Smithy Holdings Limited | Financial services | 2021 |
| Smjc Property Limited | Financial services | 2025 |
| SMS Food Equipment Ltd | Wholesale & retail | 2022 |
| SMX Services Ltd | Construction | 2024 |
| Snake Charmer Limited | Wholesale & retail | 2018 |
| Snapdragon Transport Limited | Transport & logistics | 2013 |
| Snapxact Ltd | Information & communication | 2025 |
| Snowdonia Staycations Ltd | Hospitality | 2021 |
| Snpi Ltd | Real estate | 2022 |
| Soccersixes Limited | Arts & recreation | 2004 |
| Sofify Limited | Extraterritorial | 2025 |
| Sofiniti Limited | Extraterritorial | 2026 |
| Software Acquisitions Ltd | Information & communication | 2019 |
| SOK (NW) Ltd | Financial services | 2025 |
| SOK Alderley Ltd | Hospitality | 2025 |
| SOK Salford Ltd | Hospitality | 2026 |