| SJN Roofing Limited | Construction | 2025 |
| SJP Talent Limited | Administrative & support | 2026 |
| SJR Supplies Ltd | Wholesale & retail | 2010 |
| SK Business Ventures Limited | Financial services | 2021 |
| SK Sunshine Limited | Wholesale & retail | 2014 |
| SK Transport Ltd | Transport & logistics | 2024 |
| SK UK Holdings Limited | Financial services | 2024 |
| SK Venture Investments Limited | Real estate | 2023 |
| SKA Heating & Plumbing Ltd | Construction | 2015 |
| Skbusybuys Ltd | Wholesale & retail | 2026 |
| Skcl Ltd | Construction | 2013 |
| Skillec Limited | Construction | 2015 |
| Skilled Roofing Limited | Construction | 2020 |
| Skilling for Life Ltd | Professional & scientific | 2012 |
| Skin & Sculpt Aesthetics Ltd | Other services | 2026 |
| Skin LAB Studio Ltd | Wholesale & retail | 2026 |
| Skor Ltd | Real estate | 2022 |
| Skull X Ltd | Wholesale & retail | 2017 |
| Skulpt Hair & Beauty Ltd | Other services | 2023 |
| Sky Personnel Limited | Administrative & support | 1987 |
| Sky Wool Ltd | Information & communication | 2025 |
| Skybridge Chauffeurs Ltd | Transport & logistics | 2026 |
| Skye Blue IFA Limited | Professional & scientific | 2013 |
| Skye Green Solar Farm Limited | Energy | 2023 |
| Skyfall Creative Limited | Information & communication | 2016 |
| Skyfox Hub Limited | Information & communication | 2025 |
| Skyhawke Technologies UK Ltd | Wholesale & retail | 2006 |
| Skyla ENG Ltd | Professional & scientific | 2025 |
| Skyla Holdings Limited | Real estate | 2021 |
| Skylark Cafe Limited | Hospitality | 2026 |
| Skylark Ceramics and Glassware Ltd | Wholesale & retail | 2024 |
| Skyline Wireless Limited | Information & communication | 2018 |
| Skypher Limited | Information & communication | 2024 |
| Skyrecruitmentuk Ltd | Administrative & support | 2024 |
| Skyrise Assets Ltd | Real estate | 2023 |
| SL Drainage Solutions Ltd | Water & waste | 2025 |
| SL Projects Limited | Professional & scientific | 2013 |
| Slab London Limited | Professional & scientific | 2020 |
| Slaney Apparel Ltd | Wholesale & retail | 2025 |
| Slap Slap Ltd | Hospitality | 2025 |
| SLATE75 Limited | Wholesale & retail | 2023 |
| Slatter & Sons Contractors Ltd | Construction | 2023 |
| SLH Garden Maintenance Ltd | Construction | 2023 |
| SLH Properties Limited | Construction | 2022 |
| Slice Aylesbury Limited | Hospitality | 2026 |
| Slick Enforcement Ltd | Administrative & support | 2022 |
| Slimrchat Group Limited | Information & communication | 2024 |
| Slow Lane Travels Ltd | Administrative & support | 2021 |
| SLP Accountancy Ltd | Professional & scientific | 2021 |
| SM Affinity Ltd | Administrative & support | 2023 |
| SM Home Solutions Ltd | Construction | 2024 |
| Small BIZ Accounting Limited | Professional & scientific | 2017 |
| Small Developments Ltd | Real estate | 2016 |
| Smart Caribbean Imports Ltd | Wholesale & retail | 2023 |
| Smart Fast Solutions Ltd | Wholesale & retail | 2026 |
| Smart Finance Services Ltd | Professional & scientific | 2024 |
| Smart Medics (London) Limited | Health & social care | 2017 |
| Smart Price Motors Ltd | Wholesale & retail | 2025 |
| Smart Tutoring Limited | Education | 2017 |
| Smartcornerstore Limited | Wholesale & retail | 2026 |
| Smartelectrogear Limited | Wholesale & retail | 2025 |
| Smarter Edge Ltd | Wholesale & retail | 2015 |
| Smarter Marketing Solutions Ltd | Other services | 2021 |
| Smartplus Solution Limited | Health & social care | 2014 |
| Smartstruct Build Ltd | Construction | 2025 |
| Smarttechvr Ltd | Information & communication | 2019 |
| Smartydeals Ltd | Wholesale & retail | 2025 |
| Smashing Grace Investments Ltd | Real estate | 2025 |
| Smashing Windows Ltd | Construction | 2005 |
| Smashingwindows.Com Limited | Construction | 2003 |
| SMB Services Ltd | Professional & scientific | 2024 |
| SMD Painting Decorations Limited | Construction | 2025 |
| SMI Plumbing and Heating Ltd | Construction | 2023 |
| Smile Design Dental Ltd | Health & social care | 2013 |
| Smilecrafters Ltd | Health & social care | 2026 |
| Smileline Consulting Limited | Professional & scientific | 2025 |
| Smiles Aylesbury | Arts & recreation | 2013 |
| Smith Bailey Business Services Limited | Professional & scientific | 2018 |
| Smiths of Aston Ltd | Wholesale & retail | 2018 |
| Smithwick Partners Ltd | Professional & scientific | 2015 |
| Smokin Donut Ltd | Professional & scientific | 2010 |
| Smoking Rocket Media Ltd | Information & communication | 2017 |
| Smooth Criminal Clothing Ltd | Wholesale & retail | 2021 |
| SMP Live-In Care Services Ltd | Health & social care | 2026 |
| Smym Ltd | Hospitality | 2025 |
| SN Plumbing Solutions Ltd | Construction | 2023 |
| SN Pro Beyond Ltd | Real estate | 2024 |
| Snaffling PIG Limited | Manufacturing | 2013 |
| Snake Bite Books Ltd | Information & communication | 2024 |
| Snax of India Ltd | Wholesale & retail | 2025 |
| Snehaleela PVT Ltd | Information & communication | 2018 |
| Snfire Ltd | Construction | 2025 |
| Snhm Engineering Ltd | Information & communication | 2026 |
| Sniege Store Ltd | Wholesale & retail | 2024 |
| SNK Design Ltd | Construction | 2018 |
| SNS UK Transport Limited | Transport & logistics | 2024 |
| Soakt Ltd | Manufacturing | 2026 |
| Soaring (Oxford) Limited | Professional & scientific | 1976 |
| Soberton Capital Limited | Professional & scientific | 2026 |
| Social Aware Limited | Information & communication | 2025 |