| Skies Scaffolding Ltd | Construction | 2024 |
| Skillz Cricket Academy LLP | | 2022 |
| Skin Rejuvenation Doctor Ltd | Health & social care | 2020 |
| Skinnovation NOW Limited | Other services | 2020 |
| Skip Services Southeast Ltd | Water & waste | 2023 |
| Skipper Associates Ltd | Professional & scientific | 2024 |
| Skjp Dental Ltd | Health & social care | 2024 |
| SKM & Sons Limited | Wholesale & retail | 2025 |
| SKS Dental Ltd | Health & social care | 2020 |
| Sksp (UK) Hold Co Ltd | Health & social care | 2024 |
| Sksp Private Limited | Health & social care | 2017 |
| Sktt Limited | Health & social care | 2025 |
| Sky Iron Ltd | Information & communication | 2018 |
| Skyfall Capital Ltd | Financial services | 2019 |
| Slick Braces Ltd | Real estate | 2026 |
| SLS Electrical Solutions Ltd | Construction | 2022 |
| SLS Groundworks and Civils Ltd | Construction | 2025 |
| SM Building & Renovations Ltd | Construction | 2019 |
| Sm-Hs Infinite Limited | Health & social care | 2023 |
| Small Build Property Maintenance Ltd | Construction | 2020 |
| Small City Limited | Health & social care | 2019 |
| Smart Business Support Ltd | Administrative & support | 2022 |
| Smart Electrical Solutions Limited | Administrative & support | 2026 |
| Smart Services (Eastbourne) Limited | Administrative & support | 2013 |
| Smart Solutions Engineers Limited | Construction | 2020 |
| Smart Space Investments Limited | Real estate | 2024 |
| Smart Tech Shade Ltd | Wholesale & retail | 2017 |
| Smartclicks Media Limited | Information & communication | 2025 |
| Smartdata Engineering Ltd | Administrative & support | 2022 |
| Smarter Analytics Solutions Ltd | Information & communication | 2025 |
| Smarter Software Limited | Information & communication | 1998 |
| Smartsway Hotel and Wellness Limited | Hospitality | 2023 |
| Smartsway Limited | Professional & scientific | 2013 |
| Smartway Properties Limited | Real estate | 2018 |
| Smash and Dash Brighton Ltd | Hospitality | 2026 |
| SMB Fitness (Eastbourne) Limited | Arts & recreation | 2008 |
| SME Group Holdings Limited | Financial services | 2020 |
| SME IT Solutions Limited | Information & communication | 2012 |
| SME Procurement Consultants Ltd | Professional & scientific | 2015 |
| Smile Care Centre Limited | Health & social care | 2011 |
| Smile Dental Implants Limited | Health & social care | 2021 |
| Smile Health by Sofia Dias Ltd | Health & social care | 2022 |
| Smile Sense Limited | Health & social care | 2009 |
| Smilecare Dental Clinic Limited | Health & social care | 2010 |
| Smilehaus Ltd | Health & social care | 2025 |
| Smilelink Limited | Health & social care | 2021 |
| Smiles by Keshav Kapoor Ltd | Health & social care | 2024 |
| Smiles by TOM Limited | Health & social care | 2024 |
| Smitam Ltd | Health & social care | 2021 |
| SMJ Plumbing and GAS Services Ltd | Construction | 2019 |
| Smogmonster Limited | Arts & recreation | 2023 |
| Smokescreen Visuals Ltd | Information & communication | 2005 |
| Smokey Oak Barbecue Limited | Hospitality | 2018 |
| Smsk Prosthodontics Limited | Health & social care | 2025 |
| SMV Detailing Ltd | Wholesale & retail | 2025 |
| SN ENT Ltd | Health & social care | 2020 |
| Snail Banquet Ltd | Transport & logistics | 2022 |
| Snapped Arts CIC | Education | 2021 |
| Sncalder Ltd | Wholesale & retail | 2025 |
| Snooze Hotels Limited | Hospitality | 2012 |
| Snow OS Ltd | Information & communication | 2024 |
| SNS Management Ltd | Hospitality | 2024 |
| Snugly Ltd | Hospitality | 2025 |
| SO Legal Limited | Professional & scientific | 2015 |
| SO Romantic Ltd | Information & communication | 2018 |
| Socarrat Holding Group Ltd | Hospitality | 2022 |
| Social Media Doctor Limited | Professional & scientific | 2025 |
| Social Media First Limited | Professional & scientific | 2015 |
| Sofali Ltd | Professional & scientific | 2021 |
| Softest Consulting Ltd | Information & communication | 2023 |
| Soho Shots Pictures Ltd | Information & communication | 2025 |
| SOL Moves Limited | Transport & logistics | 2019 |
| Solareconomy Limited | Extraterritorial | 1990 |
| Solid CON Roofs Limited | Construction | 2022 |
| Solid Conservatory Roofs Limited | Construction | 2016 |
| Solmann Ltd | Construction | 2018 |
| Solo Pasta Sussex Limited | Hospitality | 2017 |
| Solo Plumbing and Heating Ltd | Construction | 2019 |
| Solo Wellness Studio Limited | Arts & recreation | 2025 |
| Solution Master Accounts Ltd | Professional & scientific | 2013 |
| Solution Master Ltd | Professional & scientific | 2021 |
| Solved Properties Ltd | Real estate | 2019 |
| Sondes Films Ltd | Information & communication | 2020 |
| Song’S Sussex Limited | Hospitality | 2020 |
| Sonicsafe Limited | Manufacturing | 2012 |
| Sonny Maintenance (Holdings) Limited | Financial services | 2016 |
| Sonny Maintenance Limited | Construction | 2002 |
| Sons of Guns Studio Ltd | Information & communication | 2023 |
| Sophia Interiors Ltd | Wholesale & retail | 2019 |
| Sophia Victoria Joy Limited | Professional & scientific | 2012 |
| Sophie Bradbury Limited | Information & communication | 2024 |
| Sophie Jayne Hair Ltd | Other services | 2022 |
| Sora Creative Limited | Professional & scientific | 2022 |
| Soran Ltd | Wholesale & retail | 2024 |
| Soreva Ltd | Administrative & support | 2025 |
| Sorrell & Clarke Limited | Financial services | 2026 |
| Sorsa Jewellery Limited | Wholesale & retail | 2019 |
| Sortd Software Ltd | Information & communication | 2026 |
| Sossigedog Limited | Extraterritorial | 2017 |
| Sotto Bar Limited | Hospitality | 2025 |