| Seven Dials (Fashion) Co. Limited | Wholesale & retail | 1992 |
| SEZ Property Management Ltd | Real estate | 2025 |
| SFM Bars Ltd | Hospitality | 2020 |
| SG5 Partnership Ltd | Administrative & support | 2023 |
| Shaa Herts Ltd | Hospitality | 2018 |
| Shah Capital Limited | Real estate | 2015 |
| Shah Capital Trading Limited | Real estate | 2017 |
| Shah Realty Limited | Real estate | 2017 |
| Shalstone Road Ltd | Households | 2025 |
| Shanahan Contracting Ltd | Water & waste | 2010 |
| Shanara Coaching Limited | Professional & scientific | 2026 |
| Shanasham Limited | Households | 2025 |
| Shane Raymond Online Coaching Limited | Arts & recreation | 2023 |
| Shanks Power Solutions Ltd | Manufacturing | 2010 |
| Shaped Interiors & Joinery Ltd | Construction | 2021 |
| Shapla Pharma Limited | Health & social care | 2024 |
| Sharky's Soccer School Ltd | Education | 2024 |
| Sharp Security Systems Ltd | Administrative & support | 2009 |
| Sharpfitt Ltd | Construction | 2022 |
| Shatchi Limited | Wholesale & retail | 2022 |
| Shatchi Properties Ltd | Real estate | 2020 |
| Sherbrooke Lettings Ltd | Real estate | 2022 |
| Sherdel Thirnbeck Acquisitions Limited | Construction | 2013 |
| Shiaba Consulting Ltd | Professional & scientific | 2025 |
| Shiels Safe Ltd | Professional & scientific | 2026 |
| Shillelagh Solutions Limited | Professional & scientific | 2026 |
| Shilling Solutions Ltd | Information & communication | 2018 |
| Shillingoak Group Limited | Construction | 2023 |
| Shimco Properties Limited | Real estate | 2023 |
| Shine Bright Visuals Limited | Manufacturing | 2024 |
| Shinex Cleaning Services Ltd | Administrative & support | 2026 |
| Shinners Post Ltd | Professional & scientific | 2026 |
| Shiva Property Ltd | Hospitality | 2025 |
| Shiveer Property Limited | Real estate | 2022 |
| Shore Performance Limited | Other services | 2022 |
| Shorrock Automotive Ltd | Wholesale & retail | 2024 |
| Shortek Limited | Real estate | 2014 |
| Shorters Limited | Wholesale & retail | 2012 |
| Showtime Media Services Limited | Information & communication | 1994 |
| Shredx Media and Document Services Limited | Administrative & support | 2009 |
| Shreem Investments Ltd | Real estate | 2020 |
| SHREEM8891 Holdings Limited | Financial services | 2026 |
| Shrunetts Limited | Real estate | 2016 |
| Siam Square Catering UK Limited | Professional & scientific | 2017 |
| Sian Jenkins Consulting Ltd | Professional & scientific | 2026 |
| Sidhu Builders Limited | Construction | 2005 |
| Siege One Limited | Professional & scientific | 2026 |
| Siekkeris Elite Limited | Real estate | 2026 |
| Sigmacore Solutions Limited | Professional & scientific | 2024 |
| Silver Birch Florist Limited | Wholesale & retail | 2009 |
| Silver Birches Residents Limited | Households | 2006 |
| Silver Excellence Ltd | Administrative & support | 2025 |
| Silver Oak Enterprises Limited | Real estate | 2001 |
| Silverbridge Investments 1 Ltd | Real estate | 2026 |
| Silverbridge Investments 2 Ltd | Real estate | 2026 |
| Silvey Sports Ltd | Arts & recreation | 2011 |
| SIM Autos Ltd | Wholesale & retail | 2021 |
| Simkrish Securities Limited | Real estate | 2021 |
| Simmonds Investments Limited | Professional & scientific | 2000 |
| Simmons Renewables Limited | Construction | 2024 |
| Simple Solution Properties Ltd | Real estate | 2020 |
| Simpletraining Limited | Education | 2004 |
| Simplex Consulting Limited | Professional & scientific | 2014 |
| Simply Careers Ltd | Professional & scientific | 2010 |
| Simply Clophill Limited | Construction | 2021 |
| Simply Great Catering Limited | Hospitality | 2016 |
| Sincre Limited | Other services | 2010 |
| Sindoor Operation Limited | Information & communication | 2025 |
| Sinkovich Ltd | Professional & scientific | 2024 |
| Sino West Business Consultancy Limited | Professional & scientific | 2003 |
| Sinyu Limited | Wholesale & retail | 2022 |
| SIR Lancelot Awards Ltd | Professional & scientific | 2026 |
| Sita & Sons Investments Limited | Financial services | 2025 |
| Site Management Software Ltd | Information & communication | 2017 |
| Site Supplies and Services Ltd | Construction | 2004 |
| Sitiluso Limited | Hospitality | 2015 |
| Sixth Sense Intel Limited | Information & communication | 2026 |
| Sixty-Four (2015) Limited | Professional & scientific | 2015 |
| Size Zero Limited | Extraterritorial | 2007 |
| SJJ70 Ltd | Construction | 2026 |
| SJK Business Consulting Ltd | Professional & scientific | 2023 |
| SJS Carpentry Solutions Ltd | Manufacturing | 2014 |
| SJT Electrical Limited | Construction | 2020 |
| SK Medical Services Ltd | Health & social care | 2019 |
| SK Sporthorses Ltd. | Agriculture & fishing | 2016 |
| Skeptical Music UK Ltd | Information & communication | 2015 |
| Skill Csar Limited | Manufacturing | 2022 |
| Skillmatch Recruitment Ltd | Administrative & support | 2021 |
| Skills Training Agency Limited | Administrative & support | 1989 |
| Skin Haven by Jessica Ltd | Other services | 2023 |
| Skininspire Ltd | Health & social care | 2020 |
| Skoen Food and Logistics Ltd | Transport & logistics | 2024 |
| Skratch Group Ltd | Arts & recreation | 2022 |
| Sky Cluster Limited | Manufacturing | 2014 |
| Sky Plastics Limited | Wholesale & retail | 2020 |
| Skye FOX Limited | Information & communication | 2021 |
| Skyeastof Limited | Professional & scientific | 2000 |
| Skyline Consult Limited | Real estate | 2023 |
| Skyone Properties Ltd. | Real estate | 2017 |
| Skyra Properties Limited | Real estate | 2019 |