| Simpatico (Homecare) Ltd | Health & social care | 2024 |
| Simpatico Consultancy Ltd | Professional & scientific | 2020 |
| Simpillcarepac Ltd | Professional & scientific | 2011 |
| Simple Build Projects Ltd | Construction | 2026 |
| Simple Electrical Services Limited | Construction | 2018 |
| Simple Energy Holdings Ltd | Financial services | 2024 |
| Simple Energy Services Ltd | Administrative & support | 2017 |
| Simple Energy Subscription Ltd | Energy | 2023 |
| Simple Energy Systems Ltd | Professional & scientific | 2011 |
| Simple Links IT Limited | Information & communication | 2018 |
| Simple Property Developments Ltd | Real estate | 2020 |
| Simple Retrofit Ltd | Construction | 2024 |
| Simple Solutions (Liverpool) Ltd | Construction | 2020 |
| Simplex Cables (UK) Ltd | Manufacturing | 2017 |
| Simplicity Claims Ltd | Administrative & support | 2025 |
| Simply Air Conditioning Limited | Energy | 2020 |
| Simply Bathrooms (UK) Limited | Wholesale & retail | 2010 |
| Simply Beauty (Formby) Ltd | Other services | 2017 |
| Simply Beauty Liverpool Limited | Other services | 2022 |
| Simply Blinds Liverpool Limited | Manufacturing | 2019 |
| Simply Deco Ltd | Construction | 2018 |
| Simply Delicious (Bootle) Ltd | Hospitality | 2024 |
| Simply Developments NW Ltd | Real estate | 2023 |
| Simply Diverse Ltd | Real estate | 2018 |
| Simply Furniture Limited | Wholesale & retail | 2016 |
| Simply Housework (UK) Ltd | Other services | 2008 |
| Simply Installations Peterborough Ltd | Construction | 2022 |
| Simply Loaded Ltd | Hospitality | 2024 |
| Simply Locums Ltd | Administrative & support | 2016 |
| Simply Property Investments Ltd | Real estate | 2019 |
| Simply Property Specialists Ltd | Construction | 2015 |
| Simply Serene CIC | Hospitality | 2025 |
| Simply Signs Northwest Limited | Professional & scientific | 2009 |
| Simply Social Housing Ltd | Professional & scientific | 2010 |
| Simply Sugar 2 Ltd | Wholesale & retail | 2015 |
| Simply Tickets Ltd | Administrative & support | 2010 |
| Simply Vibrant Liverpool Ltd | Wholesale & retail | 2022 |
| Simply-People Ltd | Professional & scientific | 2019 |
| Simply-Raw North Wales Ltd | Administrative & support | 2017 |
| Simplybiometrics Limited | Other services | 2006 |
| Simplyendo LLP | | 2016 |
| Simpson Trading Ltd | Wholesale & retail | 2020 |
| Simpson’S NW Plumbing & Heating Ltd | Construction | 2018 |
| Simran's News Limited | Wholesale & retail | 2017 |
| Simsek Restaurant Ltd | Hospitality | 2020 |
| Simtrad Property Services Limited | Real estate | 2017 |
| Simukai Care Services Ltd | Health & social care | 2015 |
| Simul Software Ltd | Information & communication | 2007 |
| Simwell Enterprises Ltd | Real estate | 1999 |
| Sina BCP Ltd | Hospitality | 2026 |
| Sina Construction Ltd | Real estate | 2017 |
| Sina Motors UK Ltd | Wholesale & retail | 2026 |
| Sina Property Company Ltd | Real estate | 2020 |
| Sina Restaurant Ltd | Hospitality | 2024 |
| Sina Signature Properties Ltd | Hospitality | 2026 |
| Sinan Eats Ltd | Hospitality | 2020 |
| SINCE1878 Events Limited | Hospitality | 2025 |
| SINCE1878 Memorabilia Limited | Other services | 2025 |
| Sinckler Care Ltd | Health & social care | 2025 |
| Sinclair Accounting Co. Ltd | Professional & scientific | 2005 |
| Sinclair Accounting Limited | Professional & scientific | 2012 |
| Sinclair Method UK Ltd | Health & social care | 2019 |
| Sinclair Secretarial Services (UK) Ltd | Extraterritorial | 2007 |
| Sine Missione Ltd | Administrative & support | 2017 |
| Sing Faye Liverpool Ltd | Hospitality | 2023 |
| Sing Sing Empire Limited | Real estate | 2021 |
| Singh&Sons Developments Limited | Construction | 2026 |
| Single Level Luxury Limited | Construction | 2023 |
| Single Origin Coffee Co. Limited | Wholesale & retail | 2025 |
| Single PLY Solutions (NW) Ltd | Other services | 2022 |
| Singlelec Limited | Construction | 2015 |
| Singleton Investment Company Limited | Real estate | 1925 |
| Singleton Spencer Ltd | Administrative & support | 2017 |
| Singleton Spencer Property Ltd | Real estate | 2026 |
| Sinistra Developments Ltd | Construction | 2024 |
| Sinistra Ltd | Construction | 2024 |
| Sink Recordings LLP | | 2025 |
| Sino Swan Holdings Ltd | Real estate | 2018 |
| Sino Swan Ltd | Real estate | 2019 |
| Sinoway Education Ltd | Administrative & support | 2025 |
| Sinoway Properties Limited | Real estate | 2016 |
| Sinsations Ltd | Wholesale & retail | 2020 |
| Sintons Property Services Ltd | Construction | 2026 |
| Sintricate Solutions Ltd | Professional & scientific | 2025 |
| Siop Nain Ltd | Wholesale & retail | 2013 |
| SIP Building Systems Limited | Construction | 2004 |
| SIP Builduk Limited | Construction | 2022 |
| SIP City Store Ltd | Wholesale & retail | 2023 |
| SIP Dopa Ltd | Manufacturing | 2026 |
| SIP N Twist Liverpool Ltd | Manufacturing | 2025 |
| Sipco Ltd. | Manufacturing | 2010 |
| Sipi Trans Limited | Transport & logistics | 2024 |
| Sipp Specialists Limited | Extraterritorial | 2003 |
| Sipside Ltd | Wholesale & retail | 2025 |
| SIR Thomas Developments Ltd | Real estate | 2019 |
| SIR Thomas Ltd | Real estate | 2014 |
| Siren Fire & Security Ltd | Construction | 2021 |
| Siren Styling Ltd | Wholesale & retail | 2025 |
| Siren Transport Ltd | Transport & logistics | 2023 |
| Siri Homes and Properties Ltd | Real estate | 2021 |