| Silverkey Consulting Limited | Professional & scientific | 2025 |
| Silverlake Group Ltd | Hospitality | 2026 |
| Silverline Worldwide L.P. | | 2018 |
| Simaura Properties Limited | Real estate | 2026 |
| Simms Business Consultancy Limited | Professional & scientific | 2025 |
| Simpapps Ltd | Information & communication | 2026 |
| Simpler Homes Limited | Construction | 2024 |
| Simply Aysha Ltd | Wholesale & retail | 2024 |
| Simply Buying Services Ltd | Wholesale & retail | 2024 |
| Simply Heritage Ltd | Wholesale & retail | 2023 |
| Simply Markets Group Ltd | Information & communication | 2020 |
| Simply Savvy Limited | Information & communication | 2026 |
| Simply Serviced Accommodation Ltd | Hospitality | 2021 |
| Simply Spines Limited | Health & social care | 2005 |
| Simplypharma Consulting Limited | Professional & scientific | 2025 |
| Simpro Ltd | Real estate | 2025 |
| Simsbuddy Ltd | Education | 2025 |
| Simson Limited | Other services | 2014 |
| Simumed Ltd | Education | 2022 |
| Sinan Compass Limited | Extraterritorial | 2016 |
| Sinan Trading Limited | Extraterritorial | 2016 |
| Sincere Time SEE Ltd | Wholesale & retail | 2025 |
| Sincereda Ltd | Wholesale & retail | 2026 |
| Sinchi Ltd | Health & social care | 2022 |
| Single Minded Strategy Group Limited | Professional & scientific | 2025 |
| Sings OUT Music Creative Arts UK CIC | Education | 2026 |
| Sinosource Ltd | Professional & scientific | 2026 |
| Sinovus Global Ltd | Wholesale & retail | 2025 |
| SIR Shisha Ltd | Wholesale & retail | 2025 |
| Sircaesar Limited | Information & communication | 2017 |
| Siren Events Ltd | Arts & recreation | 2025 |
| Sirius Talent Recruitment Solutions Limited | Administrative & support | 2024 |
| Sirius Travel Recruitment Solutions Limited | Administrative & support | 2024 |
| Sisa Business Services Limited | Information & communication | 2009 |
| Sisters Protect Ltd | Education | 2025 |
| Siteframe Security Ltd | Administrative & support | 2026 |
| Situation Pictures Ltd | Information & communication | 2026 |
| Sixpad Ltd | Wholesale & retail | 2026 |
| Sixtel Limited | Information & communication | 2023 |
| Sixth Avenue Events Ltd | Other services | 2025 |
| Sixtyllionaire Ltd | Financial services | 2024 |
| Sizzle Online Ltd | Information & communication | 2022 |
| Sjistic Ltd | Information & communication | 2021 |
| SK Noble Ltd | Wholesale & retail | 2025 |
| SK Residences Ltd | Real estate | 2021 |
| Skhann Ltd | Professional & scientific | 2023 |
| SKI11 Ltd | Other services | 2023 |
| Skill Clique CIC | Information & communication | 2022 |
| Skill Forge IO Ltd | Information & communication | 2026 |
| Skillify AB UK Ltd | Education | 2025 |
| Skillplus Global Ltd | Wholesale & retail | 2025 |
| Skin KIN Limited | Manufacturing | 2024 |
| Skinn Aesthetics Ltd | Other services | 2023 |
| Skora Ltd | Wholesale & retail | 2025 |
| Sky Business Services Limited | Professional & scientific | 2011 |
| Sky Developments Ltd | Real estate | 2018 |
| Sky Global Group Ltd | Wholesale & retail | 2026 |
| Sky Horizon Services Ltd | Information & communication | 2025 |
| Sky Host Ltd | Wholesale & retail | 2025 |
| Sky Marine Tourism Limited | Professional & scientific | 2025 |
| Sky Samerset Ltd | Wholesale & retail | 2024 |
| Skychock Ltd | Information & communication | 2018 |
| Skye Consulting Group Limited | Information & communication | 2024 |
| Skyetic Ltd | Information & communication | 2025 |
| Skylab Industries Ltd | Manufacturing | 2026 |
| Skynexora Ltd | Manufacturing | 2026 |
| Skyrocket Ltd | Other services | 2025 |
| Slade Enterprise Group Ltd | Other services | 2024 |
| Slate&Cue Limited | Wholesale & retail | 2026 |
| SLD International Exports (China) Ltd | Arts & recreation | 2026 |
| Sleepy Nailzzz Ltd | Other services | 2024 |
| SLH Global Limited | Wholesale & retail | 2026 |
| Slice ‘N’ Easy Mobile Pizza Limited | Hospitality | 2025 |
| Slimpets Ltd | Extraterritorial | 2024 |
| Slippy Clouds Ltd | Professional & scientific | 2022 |
| Sloe Wood Ltd | Manufacturing | 2024 |
| Slon Group Limited | Extraterritorial | 2022 |
| Sloxen Ltd | Information & communication | 2025 |
| SLS Locksmiths Ltd | Real estate | 2008 |
| Slumber Brands Ltd | Wholesale & retail | 2025 |
| Slydragon Ltd | Wholesale & retail | 2025 |
| SM Concept LLP | | 2024 |
| Smallshaw Lettings Limited | Real estate | 2025 |
| Smaragdus Store Ltd | Wholesale & retail | 2023 |
| Smart Apps Ltd | Information & communication | 2022 |
| Smart Carbon Consulting Ltd | Professional & scientific | 2024 |
| Smart Decor Hub Ltd | Wholesale & retail | 2023 |
| Smart Home Resources Ltd | Other services | 2025 |
| Smart Royl AI Ltd | Education | 2026 |
| Smart Scale Solutions Ltd | Information & communication | 2025 |
| Smart Skills Academy Ltd | Information & communication | 2025 |
| Smart Watch Earth Limited | Education | 2025 |
| SMART4TECH Ltd. | Information & communication | 2016 |
| Smarter Properties Ltd | Real estate | 2017 |
| Smartglyph Limited | Information & communication | 2012 |
| Smartgt Ltd | Information & communication | 2021 |
| Smartweb Specialist Limited | Information & communication | 2017 |
| Smash London Ltd | Health & social care | 2019 |
| SME Marketer Limited | Professional & scientific | 2020 |
| Smilesoft Limited | Information & communication | 2024 |