| Salcey Consulting Ltd | Information & communication | 2022 |
| Salcey Investments Ltd | Real estate | 2020 |
| SALON1THIRTY4 Ltd | Other services | 2018 |
| Samantha Nicole Optical Limited | Wholesale & retail | 2023 |
| Sanctuary Healthcare Ltd | Health & social care | 2025 |
| Sandbanks Place Residents Limited | Households | 2015 |
| Santa Care Limited | Administrative & support | 2014 |
| SARGENTS3 Ltd | Professional & scientific | 2012 |
| Saturn EV Ltd | Wholesale & retail | 2018 |
| SB Sign Installations Ltd | Construction | 2021 |
| SB1180 Limited | Professional & scientific | 2020 |
| Scaffx Limited | Construction | 2020 |
| Scarlets Beauty Salon Limited | Other services | 2011 |
| Scene on Screen Ltd | Construction | 2019 |
| Scenic Constructions Ltd. | Construction | 2013 |
| Scientia Construction Limited | Construction | 2024 |
| Scooty Ltd | Wholesale & retail | 2020 |
| Scorpion Climate Limited | Wholesale & retail | 2014 |
| Scrap My Car Eastbourne Ltd | Wholesale & retail | 2023 |
| Scrumdiddlyumptious Hailsham Ltd | Wholesale & retail | 2025 |
| Sculptclinic Ltd | Health & social care | 2024 |
| SD Wardle Ltd | Health & social care | 2025 |
| SDP Developments Limited | Construction | 2010 |
| SE1 Management Limited | Real estate | 2026 |
| SE1 Xxvi Limited | Financial services | 2026 |
| Seabrook Vale Management Company Limited | Real estate | 2008 |
| Sean Yates Cycling Limited | Arts & recreation | 2013 |
| Seaview Developments (Sussex) Ltd | Construction | 2013 |
| Secret Creation Ltd | Wholesale & retail | 2018 |
| SEL Commercials Limited | Wholesale & retail | 2020 |
| SEL Live Ltd | Arts & recreation | 2021 |
| Sellens Limited | Real estate | 2014 |
| Sellyourcarsussex Ltd | Wholesale & retail | 2025 |
| Sentry Auditing Limited | Administrative & support | 2023 |
| Sentry Portfolio Limited | Real estate | 2024 |
| Sentry Tech Limited | Financial services | 2012 |
| Sequoia Construction Limited | Construction | 1996 |
| Sequoia Events Ltd | Administrative & support | 2018 |
| Serene Global Developments Limited | Construction | 2024 |
| Seventh Art Distribution Limited | Extraterritorial | 2006 |
| Seventh Art Productions Limited | Arts & recreation | 1990 |
| SG Reed Construction and Groundworks Limited | Construction | 2021 |
| SH Utilities (Sussex) Limited | Construction | 2024 |
| Shamrock Development Co Ltd | Construction | 2022 |
| Shaping Paths Consulting Ltd | Professional & scientific | 2022 |
| Shard Holdings Ltd | Transport & logistics | 2022 |
| Sharna Richardson Ltd | Wholesale & retail | 2025 |
| Sharpe Pryce Consultants Ltd | Professional & scientific | 2023 |
| Shemithar Limited | Health & social care | 2024 |
| Sherief Elsayed Limited | Health & social care | 2010 |
| Sherlock Associates Limited | Professional & scientific | 2003 |
| Sherwood (Brondesbury) Management Limited | Real estate | 1993 |
| Shield Environmental Systems Limited | Administrative & support | 1999 |
| Shiku Logistics Ltd | Transport & logistics | 2025 |
| Shining Knight Productions Ltd | Information & communication | 2022 |
| Shining Twins Ltd | Administrative & support | 2025 |
| Shivers FM Limited | Extraterritorial | 2025 |
| Shivers Group Limited | Financial services | 2026 |
| Shivers Holdings Limited | Extraterritorial | 2025 |
| Shivers Ventilation Limited | Construction | 2017 |
| Shoreham Flying Club Limited | Arts & recreation | 2011 |
| Shoreham Hub Limited | Construction | 2026 |
| Shrewton Property Services Limited | Real estate | 2023 |
| SID Sewell Ltd | Information & communication | 2015 |
| Sierra Golf Financial Services Ltd | Financial services | 2024 |
| Sigma Geotechnical Services Limited | Professional & scientific | 2014 |
| Signtek (Worthing) Limited | Manufacturing | 2025 |
| Sikora Holdings Limited | Financial services | 2025 |
| Silver Star Cleaning Limited | Administrative & support | 2003 |
| Silver Wharf Partners LLP | | 2019 |
| Silver Wharf Services Limited | Professional & scientific | 2020 |
| Silverdale Investments (Sussex) Limited | Real estate | 2024 |
| Silverlight (MOT) Limited | Administrative & support | 2006 |
| Silverray Consulting Limited | Financial services | 2026 |
| Simes Plumbing & Heating Limited | Construction | 2016 |
| Simile Logics Limited | Information & communication | 2011 |
| Simmonds Estates Limited | Administrative & support | 2009 |
| Simple Construction Training Limited | Education | 2026 |
| Simplex Modular Limited | Professional & scientific | 2018 |
| Simply African Food Limited | Wholesale & retail | 2012 |
| Simply Installations Ltd | Construction | 2020 |
| Simply Simon UK Relocations Ltd | Hospitality | 2024 |
| Simpsons Independent Financial Advisers Limited | Administrative & support | 1999 |
| Simpsons Wealth Management LLP | | 2011 |
| SIP and Swirl Wine Bar Limited | Hospitality | 2026 |
| Siracs Holdings Ltd | Financial services | 2025 |
| Sirex Contracting Limited | Information & communication | 2002 |
| Siteline Building Products Limited | Wholesale & retail | 2013 |
| Siteline Windows Limited | Construction | 2013 |
| Sixty Seven Limited | Real estate | 2017 |
| SJ Hoskinson Orthopaedics Limited | Health & social care | 2023 |
| SJ Properties Sussex Limited | Real estate | 2020 |
| SJB Properties (Eastbourne) Limited | Real estate | 2018 |
| SJM 15 Limited | Extraterritorial | 2013 |
| SJM 18 (Holdings) Ltd | Extraterritorial | 2015 |
| SJM Homes LLP | | 2020 |
| SJR Lettings Limited | Real estate | 2025 |
| Skillsform Ltd | Extraterritorial | 2019 |
| Skiwhite Limited | Administrative & support | 2010 |
| Sky Reside Ltd | Real estate | 2025 |