| Risus Limited | Wholesale & retail | 2009 |
| Rockfort Property Group Ltd | Real estate | 2024 |
| Rockwear UK Ltd | Wholesale & retail | 2018 |
| Rolls Property Limited | Real estate | 2020 |
| Romala Design Limited | Administrative & support | 2007 |
| Roommd 2 Limited | Real estate | 2026 |
| Roommd 3 Limited | Real estate | 2026 |
| Roommd Limited | Real estate | 2025 |
| Rose Meadow Preservation Company Ltd | Households | 2021 |
| Rosehill House Management Ltd | Households | 2016 |
| Rother and Wealden Pickleball CIC | Arts & recreation | 2025 |
| Roud Engineering Ltd | Manufacturing | 2017 |
| Route 39 Digital Media Limited | Wholesale & retail | 2008 |
| Rudolf Steiner Association Limited(The) | Health & social care | 1935 |
| RW Easterby Production Limited | Professional & scientific | 2016 |
| RW Equine VET Ltd | Professional & scientific | 2019 |
| S & D Hill Developments Limited | Real estate | 2019 |
| S H Pharma Consulting Limited | Other services | 2022 |
| S J Building Ltd | Construction | 2021 |
| S.E. Estates & Agency Management Ltd | Real estate | 2002 |
| S.Eldridge Limited | Households | 2021 |
| SAA GAS Services Ltd | Construction | 2001 |
| Sableindustries Ltd | Information & communication | 2011 |
| Saffam Limited | Wholesale & retail | 2022 |
| Saltwater Angling Media Ltd | Information & communication | 2011 |
| Samuel's Group Ltd | Extraterritorial | 2016 |
| Sara Bailey Consulting Limited | Other services | 2011 |
| Sarah Gilchriest Consulting Ltd | Professional & scientific | 2026 |
| SAY Limited | Information & communication | 2005 |
| SB Decking Ltd | Construction | 2023 |
| Sblb Consulting Ltd | Professional & scientific | 2026 |
| School Booking Limited | Information & communication | 2009 |
| Science Software Development Ltd | Information & communication | 2022 |
| Scott Gilchrist Heating and Plumbing Limited | Manufacturing | 2004 |
| Scribble & Daub Ltd | Manufacturing | 2018 |
| Sea Life Styles Limited | Wholesale & retail | 2010 |
| Seabass Pictures Limited | Information & communication | 2023 |
| Seaside Campers Limited | Wholesale & retail | 2024 |
| Seaside Conversions Limited | Wholesale & retail | 2025 |
| Seek Recruit Limited | Administrative & support | 2013 |
| Senlac Business Advisory Limited | Professional & scientific | 2018 |
| Senlac Garage Limited | Wholesale & retail | 2023 |
| Senlac Storage Ltd | Administrative & support | 2009 |
| Sensory Horse | Health & social care | 2021 |
| Sharpes Property Limited | Real estate | 2025 |
| Sharsky Ltd | Information & communication | 2022 |
| Shillibeer Property Limited | Real estate | 2016 |
| Shirlea View Freehold Limited | Households | 2023 |
| Sidney Baker Designs Ltd | Manufacturing | 2022 |
| Siggs & Co Ltd | Professional & scientific | 1995 |
| Simon Creamer Plumbing and Heating Ltd | Construction | 2015 |
| SJF Substation Commissioning Ltd | Professional & scientific | 2026 |
| SL Construction Southern Ltd | Construction | 2024 |
| SLK Mobility Limited | Wholesale & retail | 2012 |
| Smallville Builders Ltd | Construction | 2011 |
| SMOKEHOUSEGRILL1066 Limited | Hospitality | 2024 |
| Smooth Operators (Battle) Limited | Other services | 2019 |
| Solaruk Limited | Manufacturing | 2000 |
| Somar Media Ltd | Information & communication | 2016 |
| Sonographic Imaging Solutions Limited | Public administration | 2024 |
| South Coast Laundry Solutions Ltd | Other services | 2024 |
| South East Wealth Management Ltd | Financial services | 2017 |
| Southeast Building Surveyors Limited | Professional & scientific | 2014 |
| Southeast Statictrader Ltd | Wholesale & retail | 2017 |
| SP Pharma Consulting Limited | Other services | 2011 |
| Space for YEW CIC | Education | 2024 |
| Speakers From the Edge Limited | Arts & recreation | 2007 |
| Spectrum Independent Financial Advice Limited | Financial services | 2015 |
| Spice Monkey Limited | Wholesale & retail | 2023 |
| Spmv Ltd | Health & social care | 2023 |
| Spring Care PAS Battle Limited | Health & social care | 2013 |
| ST Anthony's Trust Limited | Education | 2022 |
| ST Nectans Limited | Real estate | 1998 |
| Starcroft Farm Cabins Ltd | Hospitality | 2022 |
| Stay Connected Club Ltd | Health & social care | 2013 |
| Steldoon Daley Ltd | Real estate | 2021 |
| Strata Executive Ltd | Information & communication | 2025 |
| Strike Rigging and Consultancy Ltd | Information & communication | 2023 |
| Studentventure Ltd | Administrative & support | 2023 |
| Studio Rookie Limited | Professional & scientific | 2025 |
| Sunshine Yarns Ltd | Wholesale & retail | 2010 |
| Sussex Aggregate Ltd | Administrative & support | 2015 |
| Sussex Countryside Services Ltd | Agriculture & fishing | 2019 |
| Sussex Garden Solutions Limited | Administrative & support | 2021 |
| Sussex Outreach Support CIC | Health & social care | 2024 |
| Sussex Prestige Automotive Limited | Other services | 2023 |
| Sussex Roof Tiles Limited | Extraterritorial | 2006 |
| Sussex Stronghold Scaffolding Ltd | Construction | 2024 |
| Sussex Tree Fella Ltd | Administrative & support | 2019 |
| Sutton Design Studio Ltd | Professional & scientific | 2026 |
| Swain Property Holdings Ltd | Real estate | 2025 |
| Swift-Lite International Ltd | Wholesale & retail | 2011 |
| Syswright Limited | Information & communication | 1996 |
| T & L Garage Services (Leonards on Sea) Ltd | Wholesale & retail | 2025 |
| T (Property) MC Ltd | Real estate | 2022 |
| T Brunton Ltd | Construction | 2015 |
| T24 Productions Ltd | Information & communication | 2014 |
| Tanning in Battle Ltd | Other services | 2023 |
| TD Aerospace (UK) Limited | Professional & scientific | 2018 |
| Teallen Limited | Arts & recreation | 2025 |