| Silver Lining Traders Ltd | Manufacturing | 2025 |
| Silver Slik Limited | Wholesale & retail | 2024 |
| Silver Stone Contractors Ltd | Construction | 2024 |
| Silver Swan Group Ltd | Wholesale & retail | 2019 |
| Silverback Properties Limited | Real estate | 2004 |
| Silverbell Properties Limited | Real estate | 2024 |
| Silvercrest Property Maintenance Ltd | Construction | 2026 |
| Silverline Blinds Ltd | Manufacturing | 2025 |
| Silverline Electronics Ltd | Wholesale & retail | 2025 |
| Silversound (Yorkshire) Ltd | Information & communication | 2011 |
| Silverspoon Cutlery Ltd | Manufacturing | 2024 |
| Silverstone Logistics Ltd | Transport & logistics | 2023 |
| SIM Medical Ltd | Health & social care | 2022 |
| Sima (Yorkshire) Ltd | Administrative & support | 2016 |
| Sima Bashir Dent Ltd | Health & social care | 2023 |
| Sima Developments Limited | Construction | 2012 |
| Simak Collection Ltd | Wholesale & retail | 2022 |
| Simanvir Singh Mahil Consulting Ltd | Professional & scientific | 2021 |
| Simba Smoby Toys (UK) Limited | Wholesale & retail | 2009 |
| Simco Worldwide Ltd | Wholesale & retail | 2023 |
| Simcoach Ltd | Other services | 2025 |
| Simmonites Limited | Wholesale & retail | 2003 |
| Simmthornes Mechanical Services Ltd. | Construction | 2021 |
| Simmthornes Property Limited | Real estate | 2024 |
| Simon Mottram Electrical Ltd | Construction | 2024 |
| Simon White Medical Ltd | Wholesale & retail | 2012 |
| Simon Wragg Ltd | Professional & scientific | 2018 |
| Simple Cash Limited | Financial services | 2005 |
| Simple Crepe Ltd | Hospitality | 2024 |
| Simple International Ltd | Wholesale & retail | 2017 |
| Simplecare Training Academy Ltd | Health & social care | 2019 |
| Simplicitybym Ltd | Wholesale & retail | 2024 |
| Simplify Bookkeeping and Payroll Ltd | Professional & scientific | 2025 |
| Simply Business Space Limited | Real estate | 2025 |
| Simply Desserts Yorkshire Limited | Manufacturing | 2018 |
| Simply Fresh Foods Holdings Limited | Professional & scientific | 2004 |
| Simply Gifted Ltd | Other services | 2025 |
| Simply Happy Accounting Limited | Professional & scientific | 2021 |
| Simply Happy Properties Ltd | Real estate | 2007 |
| Simply Local Best One Ltd | Wholesale & retail | 2023 |
| Simply LUX Ltd | Wholesale & retail | 2025 |
| Simply Maintenance Desk Ltd | Construction | 2023 |
| Simply Nikah Limited | Information & communication | 2023 |
| Simply Ponds UK Ltd | Construction | 2021 |
| Simply Retail Manchester Ltd | Wholesale & retail | 2023 |
| Simply Traders Ltd | Wholesale & retail | 2025 |
| Simplynow Limited | Information & communication | 2023 |
| Simplypack Ltd | Wholesale & retail | 2025 |
| Simpson - Turner Ltd | Manufacturing | 2013 |
| Simpson Property Holdings Ltd | Real estate | 2025 |
| Simrans Holdings Limited | Real estate | 2020 |
| Simrans Trading Limited | Manufacturing | 2010 |
| Singh & Sons Sandygate Terrace Ltd | Wholesale & retail | 2018 |
| Singh Bagri Services Limited | Administrative & support | 2015 |
| Singh Hospitality Events Ltd | Arts & recreation | 2023 |
| Singh Innovations Limited | Hospitality | 2023 |
| Singh Shopfront & Shutters Ltd | Construction | 2025 |
| Singhs 1 Associates Limited | Hospitality | 2010 |
| Singhs 3 Associates Limited | Real estate | 2022 |
| Single Wave Ltd | Administrative & support | 2013 |
| Singto Holdings Limited | Real estate | 2016 |
| Singularitee Limited | Information & communication | 2017 |
| Sink & TAP Ltd | Wholesale & retail | 2018 |
| Siphealthandnutrition Ltd | Information & communication | 2020 |
| Siphonix Worldwide Limited | Administrative & support | 2010 |
| SIR James Hill & Sons Topmakers Limited | Extraterritorial | 2001 |
| Sirinart Bingley Ltd | Health & social care | 2024 |
| Sirinart Thai Therapy (Saltaire) Ltd | Health & social care | 2022 |
| Sirinart Thai Training Ltd | Health & social care | 2021 |
| Siriporn Thai Spa and Beauty Therapy Limited | Other services | 2015 |
| Sirius Childcare Holdings Ltd | Health & social care | 2026 |
| Sirius Childcare Ltd | Health & social care | 2025 |
| Sirius Foods Ltd | Wholesale & retail | 2020 |
| Sirjan Investments Ltd | Real estate | 2022 |
| Sirr Services Ltd | Administrative & support | 2023 |
| SIS Assist Limited | Health & social care | 2026 |
| SIS Electrical Contractors Ltd | Construction | 2022 |
| SIS Holdings Limited | Financial services | 2022 |
| SIS North Limited | Real estate | 2022 |
| SIS Project Management Ltd | Construction | 2024 |
| SIS Services Limited | Real estate | 2022 |
| Sisahh Marcom Ltd | Information & communication | 2022 |
| Siskin Financial Services Ltd | Financial services | 2011 |
| Sisterhood Fitness (Yorkshire) C.I.C. | Education | 2024 |
| Site Fencing Services Limited | Manufacturing | 2019 |
| Sitefix Joinery Ltd | Construction | 2016 |
| Sitex Decon Group Limited | Construction | 2018 |
| Sitstand Ltd | Wholesale & retail | 2020 |
| Sitti Property Developments Ltd | Real estate | 2025 |
| Sitting Room Online (BFD) Limited | Manufacturing | 2012 |
| Sity Cabs Limited | Extraterritorial | 2024 |
| Sity Drive Limited | Information & communication | 2025 |
| Sity Limited | Transport & logistics | 2023 |
| Sity Taxi Group Limited | Administrative & support | 2019 |
| Sity Taxis Limited | Financial services | 2024 |
| SIXTY6 Group Limited | Real estate | 2020 |
| SJ Global Consulting Ltd | Professional & scientific | 2026 |
| SJ Medics Ltd | Health & social care | 2016 |
| SJ Smart Investments Ltd | Real estate | 2024 |
| Sj&Co Ltd | Wholesale & retail | 2026 |