| Saxon Groundworks Ltd | Construction | 2020 |
| Sayer Property Management Limited | Real estate | 2024 |
| SB Plumbing and Heating (Sussex) Ltd | Construction | 2024 |
| Scamina Ltd | Administrative & support | 2015 |
| Scampy Jones Media Limited | Information & communication | 2008 |
| Scantech Group Ltd | Manufacturing | 2012 |
| Scantech Lithographic Limited | Manufacturing | 1995 |
| Scarfiotti Limited | Arts & recreation | 2016 |
| SCB Rail Solutions Limited | Construction | 2016 |
| Sciss Limited | Professional & scientific | 1999 |
| Scribendum Limited | Wholesale & retail | 2004 |
| SDS Engineering Limited | Professional & scientific | 2015 |
| SDS Seminars Ltd | Education | 2014 |
| Second Sound AV Ltd | Wholesale & retail | 2026 |
| September Star Investments Limited | Hospitality | 2024 |
| Seriouslee Clean Limited | Administrative & support | 2026 |
| Shack Rentals Ltd | Real estate | 2018 |
| Sharpedge Tooling Limited | Manufacturing | 2021 |
| Shaw Colegate Limited | Administrative & support | 2009 |
| Shelley Park Residents Company Limited | Real estate | 1986 |
| Sherlocks Commercial Cleaning Ltd | Administrative & support | 2024 |
| Shinger Kach Limited | Hospitality | 2022 |
| Shomiron Ltd | Education | 2022 |
| Shortridge Estates Ltd | Agriculture & fishing | 1994 |
| SHW Holdings Ltd | Real estate | 2016 |
| Signature ME Limited | Wholesale & retail | 2013 |
| Signology South Ltd | Manufacturing | 2019 |
| Simon H Wilson Limited | Administrative & support | 2009 |
| Simon Muxworthy HR Ltd | Administrative & support | 2017 |
| Simon Turner Refrigeration Services Limited | Administrative & support | 2001 |
| Simply Funding Assets Ltd | Financial services | 2018 |
| Simply Marketing Limited | Professional & scientific | 2006 |
| Simply Mortgage Matters Ltd | Financial services | 2024 |
| Simpson Tuition Ltd | Education | 2020 |
| Singularity One (UK) Limited | Mining & quarrying | 2014 |
| Sisbro Property Ltd | Hospitality | 2022 |
| Sky Guardian Ltd | Information & communication | 2025 |
| Skyhook Limited | Extraterritorial | 1979 |
| SL Skin Science Ltd | Manufacturing | 2025 |
| SLE Electrical Services Ltd | Construction | 2012 |
| Small Acre Developments Ltd | Real estate | 2017 |
| Smartypups Ltd | Wholesale & retail | 2013 |
| SMJ Automotve Limited | Wholesale & retail | 2011 |
| Snap Properties Limited | Real estate | 1999 |
| Sokada Ltd | Information & communication | 2015 |
| Soulbat Ltd | Information & communication | 2011 |
| Sounds Like UNI Ltd. | Arts & recreation | 2015 |
| South East Performing Arts CIC | Administrative & support | 2011 |
| South East Property and Land Ltd | Real estate | 2022 |
| South Lodge Heathfield Limited | Households | 2009 |
| Southern Pools GD Limited | Construction | 2025 |
| Southern Specialist Treatments Ltd | Construction | 2018 |
| Southern Steam Works Ltd | Manufacturing | 2026 |
| Sovereign Close (Eastbourne) Residents Limited | Households | 2013 |
| Space Alchemy Limited | Construction | 2002 |
| SPB Mortgage Consultants Limited | Financial services | 2010 |
| Spectrum Fine Jewellery Limited | Manufacturing | 1973 |
| SPL Mechanical Engineers Ltd | Professional & scientific | 2021 |
| Spring Hill Dressage LLP | | 2014 |
| SSZ8 Ltd | Financial services | 2025 |
| Starling Woods Ltd | Other services | 2013 |
| Sterling Lifestyle Ltd | Wholesale & retail | 2020 |
| Stevens & Billington Enterprises Ltd | Manufacturing | 2011 |
| Stevens Swim Leisure Ltd | Education | 2026 |
| Stewou Knighton Ltd | Hospitality | 2017 |
| Stir Fried Films Limited | Information & communication | 2014 |
| Story Capital Limited | Arts & recreation | 2018 |
| Strange Films and Music Ltd | Information & communication | 2017 |
| Strata Garden Design & Landscaping Limited | Administrative & support | 2014 |
| Succession Partners Ltd | Construction | 2025 |
| Supaseal (UK) Limited | Wholesale & retail | 1999 |
| Superstar Chef Limited | Hospitality | 2024 |
| Suptv Ltd | Information & communication | 2024 |
| Sussex Beer Traders Limited | Wholesale & retail | 2026 |
| Sussex Creations Ltd | Manufacturing | 2021 |
| Sussex Digital Labs Ltd | Manufacturing | 2025 |
| Sussex Grills Limited | Manufacturing | 2025 |
| Sussex Podiatrists Limited | Health & social care | 2005 |
| Sussex Property Solutions Ltd | Construction | 2018 |
| Sussex Steam Shows Limited | Arts & recreation | 2008 |
| Sussex Structures Limited | Construction | 2021 |
| Sussex Support Service C.I.C. | Health & social care | 2014 |
| Sussex TVR Limited | Wholesale & retail | 2009 |
| Sussex Water Drainage Ltd | Construction | 2021 |
| Sussex Will Writers Limited | Professional & scientific | 2023 |
| Swift Check Ltd | Administrative & support | 2006 |
| Syntego Limited | Wholesale & retail | 2005 |
| Systemactive Limited | Information & communication | 2015 |
| T Wilson Plumbing and Heating Limited | Construction | 2002 |
| T&P Properties (SW) Limited | Real estate | 2025 |
| T.W Dwellings Ltd | Construction | 2025 |
| Tacoma Properties Ltd. | Real estate | 1989 |
| Tailored Trading Ltd | Education | 2025 |
| Talent Intelligence Collective Ltd | Professional & scientific | 2021 |
| Tanners Farm Livery Yard Ltd | Agriculture & fishing | 2015 |
| Tapdeck Limited | Information & communication | 2014 |
| Tassy & Company Limited | Professional & scientific | 2011 |
| Taylor J Ltd | Hospitality | 2022 |
| Taylors J Ltd | Manufacturing | 2024 |
| TC Groundworks Sussex Ltd | Construction | 2020 |