| Simpo Deny Ltd | Transport & logistics | 2020 |
| Sims Parker and Kidd Ltd | Professional & scientific | 2020 |
| Sinai Group Limited | Wholesale & retail | 2020 |
| Sinden Limited | Professional & scientific | 2008 |
| Sinewave Energy Solutions Limited | Construction | 2015 |
| Singapore Asian Store Limited | Wholesale & retail | 2021 |
| Singlepoint Lubrication Limited | Administrative & support | 2009 |
| Singozana Ltd | Extraterritorial | 2013 |
| Sinth Music Ltd | Information & communication | 2025 |
| Sintique Property Ltd | Real estate | 2024 |
| SIP and Dine Operator Group Ltd | Hospitality | 2023 |
| SIP Panel Solutions Ltd | Construction | 2019 |
| SIR Build Alot Ltd | Construction | 2023 |
| Siramico Fulfilment Limited | Manufacturing | 2025 |
| Siramico Ltd | Manufacturing | 2019 |
| Sirma Tech Ltd | Information & communication | 2012 |
| Sirva Limited | Transport & logistics | 1992 |
| Sirva Relocation (NO.1) Limited | Transport & logistics | 1986 |
| Sirva Relocation Holdings Limited | Administrative & support | 1992 |
| Sister Alliance Limited | Wholesale & retail | 2025 |
| Site Survey 365 Limited | Information & communication | 2025 |
| Site Work Consulting Limited | Other services | 2017 |
| Sithammal Ltd | Real estate | 2019 |
| Sittampalam Ltd | Health & social care | 2023 |
| SIX K Construction. Ltd | Construction | 2025 |
| Sixintheworld Limited | Hospitality | 2025 |
| Sixmedical Ltd | Health & social care | 2023 |
| Sixty Five Roses Ltd | Administrative & support | 2018 |
| Sixty Thirty Sports Limited | Wholesale & retail | 2009 |
| Sizehigh Limited | Wholesale & retail | 2025 |
| SJ Carpentry and Pre-Fabrications Ltd | Construction | 2019 |
| SJ Group International Limited | Administrative & support | 2020 |
| SJE Hospitality Ltd | Hospitality | 2022 |
| SJH Facilities Managment Limited | Extraterritorial | 2021 |
| Sjha Ltd | Financial services | 2026 |
| SJK Health Group Limited | Health & social care | 2025 |
| SJK715 Limited | Wholesale & retail | 2021 |
| SJM Enterprises (Europe) Limited | Wholesale & retail | 2002 |
| SJP Site Services Ltd | Construction | 2026 |
| SJR Sports Ltd | Education | 2023 |
| SJS Electrical Services (Swindon) Limited | Construction | 2013 |
| SJW Transport Limited | Transport & logistics | 2018 |
| Sjwgroup Limited | Hospitality | 2025 |
| SK Consultancy Services Limited | Professional & scientific | 1992 |
| SK Hynix Nand Product Solutions UK Limited | Administrative & support | 2021 |
| Sk's Kitchen Ltd | Hospitality | 2025 |
| SK1 Retail Limited | Wholesale & retail | 2025 |
| Skaap Ltd | Professional & scientific | 2024 |
| Sketch Art and Design Limited | Professional & scientific | 2013 |
| SKG PVT Ltd | Health & social care | 2021 |
| Skgk Limited | Construction | 2018 |
| Skill UP Online Ltd | Education | 2023 |
| Skills and Knowledge Groundworks Ltd | Construction | 2025 |
| Skills Converged Limited | Information & communication | 2008 |
| Skin Graffiti Limited | Arts & recreation | 2005 |
| Skinbysherry Limited | Other services | 2025 |
| Skinpeccable Ltd | Other services | 2024 |
| Skip 123 Ltd | Professional & scientific | 2026 |
| Skip Property Limited | Real estate | 2017 |
| Skis Trees Limited | Agriculture & fishing | 2026 |
| Skitmusicservice Ltd | Education | 2026 |
| SKM Clinical Solutions Ltd | Health & social care | 2026 |
| SKN Concierge Co Ltd | Wholesale & retail | 2025 |
| SKN Private Limited | Wholesale & retail | 2022 |
| SKN Wholesales Ltd | Wholesale & retail | 2021 |
| Sky Nails Swindon Ltd | Other services | 2025 |
| Sky Tyres Ltd | Wholesale & retail | 2018 |
| Sky's the Limit Entertainment Limited | Construction | 2017 |
| SKY33 Limited | Wholesale & retail | 2023 |
| Skybeyond Consultants Ltd | Information & communication | 2025 |
| Skybound Aviation Limited | Manufacturing | 2006 |
| Skycatcher Management Limited | Agriculture & fishing | 2008 |
| Skylark Estates Ltd. | Construction | 2016 |
| Skylark Meadow (Blunsdon) Management Company Limited | Households | 2020 |
| Skylark Property Ltd | Real estate | 2021 |
| Skymarks Consultancy Limited | Information & communication | 1998 |
| Skys the Limit Drones Ltd | Professional & scientific | 2025 |
| Skytune Ltd | Wholesale & retail | 2025 |
| Skyway Industries Ltd | Information & communication | 2024 |
| Skyworthy Ltd | Professional & scientific | 2026 |
| SL Car Repair Ltd | Wholesale & retail | 2014 |
| SL Construction Horizons Ltd | Construction | 2024 |
| SL Dolhan Ltd | Construction | 2014 |
| SL Jacobs Ltd | Hospitality | 2024 |
| SL Labs Ltd | Information & communication | 2023 |
| SL Nails Ltd | Construction | 2025 |
| SL Project Management Ltd | Professional & scientific | 2022 |
| SLA EN Contexto Ltd | Information & communication | 2019 |
| Slade Motors Ltd | Wholesale & retail | 2022 |
| Slateshore Ltd | Hospitality | 2020 |
| Sleemans Trading Ltd | Wholesale & retail | 2025 |
| SLF Property Developments Ltd | Construction | 2010 |
| SLG (Leeds) Limited | Real estate | 2014 |
| Sliders Food Swindon Ltd | Hospitality | 2024 |
| Sligo (UK) Ltd. | Real estate | 2014 |
| Slinky Hair Limited | Other services | 2004 |
| Slips Sportswear Ltd | Wholesale & retail | 2025 |
| Sloan Group Limited | Construction | 2014 |
| Sloan Limited | Construction | 2009 |
| Sloane Ranger Capital Ltd | Information & communication | 2014 |