| Shubh Property Investments Ltd | Real estate | 2022 |
| Shudghar Limited | Wholesale & retail | 2026 |
| Shuffle HQ Ltd | Other services | 2021 |
| Shugu Ltd | Health & social care | 2015 |
| Shuja Corporation Ltd | Wholesale & retail | 2025 |
| Shujel Ahmed Ltd | Administrative & support | 2015 |
| Shukran Food Limited | Hospitality | 2026 |
| Shukuru Limited | Health & social care | 2013 |
| Shulin Ltd | Real estate | 2023 |
| Shumba 65 Care Limited | Administrative & support | 2014 |
| Shurdhi Ltd | Hospitality | 2023 |
| Shurovi Restaurant Limited | Hospitality | 2016 |
| Shutter UP Your Place Ltd | Wholesale & retail | 2017 |
| SHW Consultancy Ltd | Professional & scientific | 2025 |
| Shwaikh & Co Ltd | Real estate | 2026 |
| SI Cybersec Ltd | Information & communication | 2023 |
| SI Heating Ltd | Construction | 2025 |
| SI Scott Studio Limited | Arts & recreation | 2007 |
| SI Site Services Limited | Extraterritorial | 1959 |
| SI2 Consulting Ltd | Professional & scientific | 2016 |
| SIA Compliance Limited | Information & communication | 2019 |
| Sial Property Ltd | Real estate | 2026 |
| Siam Corner Ltd | Hospitality | 2025 |
| Siam Fusion Massage Ltd | Administrative & support | 2017 |
| Siam S&C Foods Ltd | Wholesale & retail | 2025 |
| Sian Johnson Services Ltd | Health & social care | 2025 |
| Sianku Limited | Information & communication | 2025 |
| Siban Ltd | Health & social care | 2013 |
| Sible Blinds Ltd | Manufacturing | 2025 |
| Sibling Bridalry Limited | Other services | 2019 |
| Sibow UK Ltd | Administrative & support | 2017 |
| Sibsom Investments Limited | Real estate | 2024 |
| Sibson Property Limited | Administrative & support | 2017 |
| SIC Enterprises Limited | Financial services | 2016 |
| SIC Projects Ltd | Construction | 2014 |
| Siciliano Pizza Yorkshire Ltd | Hospitality | 2024 |
| Sico Property Ltd | Real estate | 2026 |
| Sico Ventures Limited | Administrative & support | 2019 |
| Sicurezza 247 Ltd | Other services | 2025 |
| SID Hussain Consultancy Ltd | Public administration | 2018 |
| SID Solutions in Data Ltd | Construction | 2016 |
| SID Solutions Limited | Real estate | 2015 |
| Siddiq Medics Limited | Health & social care | 2011 |
| Side Street Express Ltd | Wholesale & retail | 2026 |
| Sidebottom Electrical Solutions Ltd | Construction | 2025 |
| Sidhom Associates Ltd. | Administrative & support | 2017 |
| Sidhu & Sons Ltd | Construction | 2020 |
| Sidhu Foods & Wine Limited | Wholesale & retail | 2019 |
| Sidr Tree Investments Ltd | Real estate | 2025 |
| SIE Vshop Ltd | Wholesale & retail | 2023 |
| Siemay Limited | Wholesale & retail | 2023 |
| Sienna Marketing Ltd | Professional & scientific | 2025 |
| Sieproperties Limited | Construction | 2024 |
| Sierra Subs UK Ltd | Construction | 2017 |
| SIG Property Co (Yorkshire) Ltd | Real estate | 2022 |
| Sight Hound Properties Ltd | Real estate | 2024 |
| Sigil Transformation Ltd | Administrative & support | 2025 |
| Sigma (Leeds) Holdings Ltd | Financial services | 2026 |
| Sigma (Leeds) Limited | Construction | 2004 |
| Sigma 100 Limited | Real estate | 2016 |
| Sigma 3 Digital Ltd | Information & communication | 2023 |
| Sigma Cortex Intelligence Ltd | Information & communication | 2026 |
| Sigma Foam Convertors Ltd | Manufacturing | 2021 |
| Sigma HAI Ltd | Professional & scientific | 2022 |
| Sigma PI Medical Legal Limited | Health & social care | 2021 |
| Sigma Utilities Holdings Limited | Wholesale & retail | 2018 |
| Sigma-Pi Healthcare Limited | Health & social care | 2019 |
| Sigma-Pi Web & AI Ltd | Public administration | 2024 |
| Sign for Success Ltd | Professional & scientific | 2023 |
| Sign Install Limited | Manufacturing | 2007 |
| Sign on Ltd | Extraterritorial | 2018 |
| Sign With Tasha and TJ Ltd | Arts & recreation | 2024 |
| Signature Beauty 17 Ltd | Other services | 2024 |
| Signature Bespoke Joinery Limited | Construction | 2024 |
| Signature Construction Projects Limited | Construction | 2023 |
| Signature England Limited | Manufacturing | 2017 |
| Signature Group Limited | Wholesale & retail | 2015 |
| Signature Hole Limited | | 2006 |
| Signature Properties by Kirsty Limited | Real estate | 2024 |
| Signature Resourcing Limited | Administrative & support | 2010 |
| Signature Stays by Fowler and Powell Limited | Real estate | 2025 |
| Signature Stays by Fowler and Powell- Rent Guarantee Limited | Real estate | 2026 |
| Signature Sweets Ltd | Wholesale & retail | 2023 |
| Signature Wills Ltd | Professional & scientific | 2013 |
| Signchain Limited | Manufacturing | 2018 |
| Signco Limited | Professional & scientific | 2024 |
| Signet Planning Limited | Professional & scientific | 2004 |
| Signifi Commercial Finance Group Limited | Financial services | 2023 |
| Signs for Success Limited | Education | 2002 |
| Signs&Keys Ltd | Manufacturing | 2019 |
| Signum Construction Limited | Construction | 2018 |
| Signworks (Leeds) Limited | Manufacturing | 2005 |
| Sigpc Developments Ltd | Construction | 2026 |
| Sihra Crank Mill Ltd | Real estate | 2023 |
| Sijoto | Financial services | 1998 |
| Sijoto (SP) | Financial services | 2021 |
| Sijoto (T) | Financial services | 2021 |
| Sika Executive Search Limited | Administrative & support | 2015 |
| Sikh Sport UK | Arts & recreation | 2011 |
| Sikikalio Services Limited | Health & social care | 2019 |