| Signature Strike Ltd | Wholesale & retail | 2026 |
| Signature Travel NW Ltd | Transport & logistics | 2026 |
| Signature Works Gold Limited | Real estate | 2017 |
| Signcode UK C.I.C. | Information & communication | 2016 |
| Signcode UK Training and Licences Limited | Education | 2017 |
| Signexa Broadcast Ltd | Information & communication | 2025 |
| Signpath Ltd | Professional & scientific | 2025 |
| Signs 3000 Ltd | Manufacturing | 2013 |
| Signs by Morrell Limited | Manufacturing | 1978 |
| Signs of a Rainbow CIC | Information & communication | 2023 |
| Signsville Limited | Health & social care | 2025 |
| Signtech Academy Limited | Education | 2025 |
| Signum Group Ltd | Manufacturing | 2015 |
| Signworks (NW) Ltd | Professional & scientific | 2020 |
| Sikaty Ltd | Information & communication | 2024 |
| Sikdeer Ltd | Wholesale & retail | 2018 |
| SIL Diagnostics Ltd | Health & social care | 2022 |
| Silan NW Limited | Hospitality | 2025 |
| Silbury 389 Limited | Real estate | 2010 |
| Silcock Engineering Ltd | Professional & scientific | 2025 |
| Silent Candle for YOU Ltd | Manufacturing | 2025 |
| Silent Whispers Ltd | Education | 2007 |
| Silipos Trading Limited | Wholesale & retail | 2016 |
| Silk BED Head Ltd | Health & social care | 2023 |
| Silk Giveaways Ltd | Wholesale & retail | 2023 |
| Silk Pure Ltd | Manufacturing | 2023 |
| Silk RD Investments Ltd | Financial services | 2019 |
| Silk Street Music Ltd | Arts & recreation | 2006 |
| Silk Style NW Ltd | Other services | 2026 |
| Silla Ltd | Wholesale & retail | 2025 |
| Sillon Services Limited | Professional & scientific | 2022 |
| Sillvote Limited | Real estate | 1986 |
| Silly Rich Ltd | Wholesale & retail | 2020 |
| Silty Pigs Hookbaits Ltd | Wholesale & retail | 2021 |
| Silva Sky Properties Limited | Real estate | 2026 |
| Silva Ventures Limited | Administrative & support | 2025 |
| Silvano Media Limited | Other services | 2007 |
| Silvano Properties Limited | Real estate | 2017 |
| Silveira Ltd | Arts & recreation | 2024 |
| Silver & Rose (Formby) Limited | Wholesale & retail | 1995 |
| Silver Bar Entertainment Ltd | Hospitality | 2018 |
| Silver Birch Golf Ltd | Hospitality | 2026 |
| Silver Birch Operations Limited | Administrative & support | 2023 |
| Silver Bird Property Limited | Real estate | 2022 |
| Silver Bridge Estates Ltd | Real estate | 2018 |
| Silver Consultants Limited | Administrative & support | 2019 |
| Silver Crest Digital Limited | Administrative & support | 2025 |
| Silver Dream Enterprises Ltd | Administrative & support | 2014 |
| Silver Fingerprint Limited | Manufacturing | 2008 |
| Silver Hammer NW Limited | Hospitality | 2019 |
| Silver Moon Consultancy Ltd | Professional & scientific | 2022 |
| Silver Origin Ltd | Administrative & support | 2025 |
| Silver Peak Construction Limited | Construction | 2019 |
| Silver Property (NW) Ltd | Households | 2013 |
| Silver Property Tech Ltd | Manufacturing | 2025 |
| Silver Shipchartering Ltd | Transport & logistics | 2021 |
| Silver Star Restaurant Limited | Hospitality | 2017 |
| Silver Tuition Limited | Education | 2020 |
| Silverbirch Estates Ltd | Real estate | 2025 |
| Silverbullet (Electrical & Mechanical) Ltd | Construction | 2013 |
| Silverdale Management (North West) Ltd | Real estate | 2023 |
| Silverdome Holdings Limited | Construction | 1991 |
| Silverdome Properties Limited | Construction | 1988 |
| Silverfox Solutions Ltd | Wholesale & retail | 2020 |
| Silverhaven Care Limited | Wholesale & retail | 2026 |
| SILVERLIGHT1441 Limited | Construction | 2026 |
| Silveroak Builders Ltd | Construction | 2026 |
| Silverpin Limited | Real estate | 2011 |
| Silverpink Ltd | Wholesale & retail | 2012 |
| Silverpoint Property Group Ltd | Real estate | 2024 |
| Silvers Street Food Ltd | Hospitality | 2025 |
| Silvershield Services Ltd | Professional & scientific | 2026 |
| Silvertree Investments Limited | Real estate | 2011 |
| Silvestrian Social Centre Community Interest Company | Hospitality | 2024 |
| Silvestrian Suites Limited | Hospitality | 2019 |
| SIM & SAJ Investments Ltd | Real estate | 2021 |
| Sima Best Services Limited | Construction | 2025 |
| Simbar Holdings Ltd | Hospitality | 2026 |
| Simchem Ltd | Professional & scientific | 2017 |
| Sime Estates Ltd | Real estate | 2025 |
| Simleo Limited | Transport & logistics | 2025 |
| Simleo Property Limited | Real estate | 2026 |
| Simm City Lettings Limited | Real estate | 2020 |
| Simmflex Ltd | Other services | 2017 |
| Simmons Caravan Services Ltd | Wholesale & retail | 2025 |
| Simolu Ltd | Professional & scientific | 2022 |
| Simon Conning Consulting Ltd | Other services | 2011 |
| Simon Davies Property Limited | Real estate | 2016 |
| Simon Gregory Consulting Ltd | Professional & scientific | 2025 |
| Simon Hyde Limited | Professional & scientific | 2022 |
| Simon Krol Limited | Construction | 2015 |
| Simon LEE Gallery Ltd | Arts & recreation | 2001 |
| Simon Mcconville Ltd | Construction | 2000 |
| Simon Pilkington Consulting Limited | Administrative & support | 2013 |
| Simon Thorne Consulting Ltd | Administrative & support | 2023 |
| Simon.J.Gibsontelecoms Ltd | Information & communication | 2025 |
| Simonmichael Ltd | Other services | 2020 |
| Simons Design Limited | Professional & scientific | 2019 |
| Simonswood Self Storage Ltd | Real estate | 2026 |
| Simonswood Skip Hire Ltd | Water & waste | 2016 |