| Sister B Services Limited | Health & social care | 2016 |
| Sisu Global Talent Ltd | Administrative & support | 2024 |
| Sitestrat Ltd | Professional & scientific | 2024 |
| Sitexzen Ltd | Information & communication | 2025 |
| Sitterpoint Ltd | Information & communication | 2021 |
| Sivan SAI Properties Limited | Real estate | 2024 |
| Sivan Shakthi Services Ltd | Wholesale & retail | 2023 |
| SIX Impossible Things Limited | Other services | 2017 |
| SIX Towns Capital SPV Ltd | Real estate | 2026 |
| SIX10 Support Solutions Ltd | Administrative & support | 2024 |
| Sixth Gear Hire Ltd | Administrative & support | 2025 |
| Siyaka Travels Ltd | Administrative & support | 2025 |
| Sizeland Pigs Limited | Agriculture & fishing | 2005 |
| Sizewell Property Hub Limited | Real estate | 2024 |
| SJ Telecoms Limited | Wholesale & retail | 2015 |
| SJ Wooldridge Consulting Ltd | Professional & scientific | 2013 |
| SJB Advisory Limited | Professional & scientific | 2022 |
| SJC Heating and Air Conditioning Ltd | Construction | 2024 |
| SJJ Construction Services Ltd | Construction | 2023 |
| Sjjm Services Limited | Health & social care | 2024 |
| SJM Customs Limited | Wholesale & retail | 2025 |
| Sjml Trading Limited | Information & communication | 2021 |
| Sjmp Healthcare Solutions Ltd | Health & social care | 2017 |
| SJP SEO Ltd | Professional & scientific | 2025 |
| SJW Fundraising Consultants Ltd | Administrative & support | 2014 |
| SK Autos Limited | Wholesale & retail | 2013 |
| SK Builderz Ltd | Construction | 2023 |
| SK Companion Properties Limited | Real estate | 2024 |
| SK Prime Enterprise Limited | Wholesale & retail | 2025 |
| SK Rental Services Limited | Real estate | 2025 |
| Skandavale Health Care Ltd | Health & social care | 2022 |
| Skathi Entertainment Limited | Information & communication | 2025 |
| Skemills Solutions Limited | Other services | 2012 |
| Skeol Ltd | Professional & scientific | 2015 |
| Skepper Wealth LLP | | 2025 |
| Skerritt Estates Ltd | Real estate | 2025 |
| SKH Incorporation Ltd | Wholesale & retail | 2026 |
| Skidmoreenterprise Limited | Wholesale & retail | 2022 |
| Skill Bridge Learning Ltd | Education | 2025 |
| Skill Threads CIC | Public administration | 2025 |
| Skillnu Ltd | Administrative & support | 2024 |
| Skills and Knowledge for the Future Ltd | Education | 2015 |
| Skillup Alliance Ltd | Administrative & support | 2025 |
| Skin Care Services Limited | Health & social care | 2019 |
| Skinfinity Bay Ltd | Other services | 2023 |
| Skinner-Smith Properties Ltd | Real estate | 2025 |
| Skipee Technologies Ltd | Information & communication | 2024 |
| SKK Vision Ltd | Information & communication | 2019 |
| Sknhd Ltd | Other services | 2025 |
| Skoosh IT Ltd | Wholesale & retail | 2021 |
| Skope Properties Limited | Real estate | 2019 |
| Skope Property Investments Limited | Real estate | 2017 |
| SKP Properties Ltd | Real estate | 2011 |
| Sktvuk CIC | Education | 2025 |
| Sky Valley Limited | Information & communication | 2026 |
| Sky Vanta Scales Ltd | Professional & scientific | 2025 |
| Sky-Light Solutions Ltd | Construction | 2023 |
| Skydive Safety Ltd | Public administration | 2024 |
| Skydome Digital Trading Technology Limited | Information & communication | 2026 |
| Skyejacked Ltd | Extraterritorial | 2023 |
| Skyhill Ltd | Wholesale & retail | 2024 |
| Skyloom Digitals Ltd | Information & communication | 2024 |
| Skyrocketer Ltd | Administrative & support | 2024 |
| Skyset Ltd | Financial services | 2020 |
| Skyward Dragon Limited | Wholesale & retail | 2026 |
| Skyward Tech Limited | Information & communication | 2026 |
| SL Mangroves Ltd | Professional & scientific | 2023 |
| SLA Advisory Ltd | Professional & scientific | 2026 |
| Sladesbars Ltd | Hospitality | 2015 |
| Slate and Beam Developments Ltd | Construction | 2026 |
| Slay Prints Ltd | Manufacturing | 2025 |
| Sleak Consultancy Ltd | Information & communication | 2022 |
| Sleepers and Scaffoldboards Limited | Wholesale & retail | 2024 |
| Sleepers Estates Ltd | Real estate | 2021 |
| Sleepwell Security & Electrical Solutions Ltd | Construction | 2018 |
| Slices to Go Ltd | Hospitality | 2026 |
| Slim NOW Ltd | Health & social care | 2025 |
| Slimcode Ltd. | Information & communication | 2010 |
| Sloanee Company Ltd | Wholesale & retail | 2026 |
| Slope Talent UK Ltd | Administrative & support | 2026 |
| Slope Tugger Ltd | Wholesale & retail | 2026 |
| Slothandsquirrel Ltd | Wholesale & retail | 2024 |
| Slowgold Clothing Company Ltd | Wholesale & retail | 2021 |
| SLR Group Holdings Limited | Real estate | 2024 |
| Sludgebusters Marine Ltd | Administrative & support | 2025 |
| Slumber Bliss Ltd | Wholesale & retail | 2023 |
| SLW Property Norfolk Ltd | Real estate | 2021 |
| SM IT Consultant Ltd | Information & communication | 2011 |
| Small Parcel Ships Ltd | Wholesale & retail | 2021 |
| Smart Care Options Ltd | Health & social care | 2017 |
| Smart Cargo Limited | Information & communication | 2025 |
| Smart Deals 23 Limited | Wholesale & retail | 2017 |
| Smart Driving Group Ltd | Education | 2023 |
| Smart Ergonomics Limited | Manufacturing | 2018 |
| Smart Glow LED Limited | Construction | 2025 |
| Smart Green Ltd | Wholesale & retail | 2008 |
| Smart Hero Limited | Information & communication | 2018 |
| Smart Home Heating Limited | Construction | 2018 |
| Smart Modular Buildings Limited | Financial services | 2019 |
| Smart Nexus Ltd | Wholesale & retail | 2026 |