| Regalpoint Properties (Sevenoaks) Limited | Construction | 2006 |
| Regalpoint Properties (Edenbridge) Limited | Real estate | 2005 |
| Regalpoint Properties (Seal) Limited | Construction | 2006 |
| Register of Qualified Genealogists | Other services | 2015 |
| Relentless Computer Solutions Limited | Information & communication | 2012 |
| Reliance Taxis (Eastbourne) Ltd | Transport & logistics | 2007 |
| Reliance Transport Executive (Southern) Ltd | Transport & logistics | 2015 |
| Renovani Ltd | Construction | 2024 |
| Rent Event Wedding, Party & Event Hire Ltd | Arts & recreation | 2018 |
| Resham Limited | Real estate | 1986 |
| Reside Sussex Ltd | Real estate | 2026 |
| Retailable Limited | Information & communication | 2019 |
| Revaivve Limited | Wholesale & retail | 2024 |
| Rhino Property Rentals Ltd | Real estate | 2022 |
| Riba Live Limited | Information & communication | 2007 |
| Richard Property Eastbourne Ltd | Real estate | 2026 |
| Ridgeway Four Management Company Limited | Households | 1998 |
| Ritrum Limited | Arts & recreation | 2003 |
| Rmmx Consulting Ltd | Administrative & support | 2025 |
| Roche Property Investments Ltd | Construction | 2024 |
| Rocky's Auto Clinic Ltd | Wholesale & retail | 2015 |
| Roebuck Anvil Properties Ltd | Real estate | 2025 |
| Rogue One Limited | Information & communication | 2020 |
| Roofing Gear Limited | Wholesale & retail | 2006 |
| Rooted Community Food CIC | Agriculture & fishing | 2019 |
| Rosey's Redecorating Ltd | Construction | 2023 |
| Ross Falconer Limited | Information & communication | 2008 |
| Rowen Developments Ltd | Construction | 2025 |
| RSUMEMES2 Ltd | Other services | 2024 |
| Rubber Dragon Limited | Information & communication | 2001 |
| Rukiya Express Ltd | Hospitality | 2020 |
| Rumbies Table Ltd | Wholesale & retail | 2019 |
| Rundem Ltd | Wholesale & retail | 2014 |
| Runn Limited | Professional & scientific | 2005 |
| RWL Building Services Ltd | Construction | 2017 |
| RYE Street Homes Ltd | Real estate | 2025 |
| S & L Creative Ltd | Professional & scientific | 2022 |
| S & M Construction Sussex Limited | Construction | 2023 |
| S Cooper Building Contractors Limited | Construction | 2005 |
| S E Smyth Construction Ltd | Construction | 2019 |
| S H Mortgage Services Limited | Financial services | 2019 |
| S.H.Maintenance Limited | Households | 1970 |
| S8 E-Training Limited | Education | 2022 |
| S8 Training Ltd | Education | 2019 |
| Sa.Davidov Ltd | Administrative & support | 2015 |
| Safe Broadcast Ltd | Professional & scientific | 2020 |
| Safe Space Security Services Limited | Administrative & support | 2005 |
| Saffrons Sports Club Ltd | Arts & recreation | 2013 |
| SAG Food & Beverage Consulting Ltd | Manufacturing | 2014 |
| Sagemaster Components Limited | Construction | 2002 |
| Sahodari London Ltd | Wholesale & retail | 2026 |
| Saint Hill Shuttle Services Ltd | Transport & logistics | 2025 |
| Salenbo Limited | Professional & scientific | 2019 |
| Salik and Miah Properties Limited | Real estate | 2025 |
| Saltoh Housing Ltd | Real estate | 2025 |
| Saltwater HR Ltd | Administrative & support | 2024 |
| Sarah Blythe LLP | | 2015 |
| Sarah Morgan Global Limited | Health & social care | 2017 |
| Satt Corporation (UK) Limited | Real estate | 2010 |
| Sausage Messaging Services Ltd | Professional & scientific | 2014 |
| Savoir Faire Accounting Limited | Professional & scientific | 2012 |
| Saxon Court Management Company Limited | Households | 1987 |
| Sayer Property Ltd | Real estate | 2021 |
| Scalex Consulting Ltd | Administrative & support | 2018 |
| Scenicspaces Ltd | Construction | 2026 |
| Scorpion Group UK Limited | Hospitality | 2005 |
| Scott Fraser Training Limited | Agriculture & fishing | 2014 |
| SDE Consulting Ltd | Professional & scientific | 2025 |
| SDS Health Ltd | Financial services | 2014 |
| SE15 Flats Ltd | Real estate | 2021 |
| Seaford Community Partnership | Administrative & support | 2004 |
| Seaford Property Centre Limited | Real estate | 1984 |
| Seagrass Blue UK Ltd | Agriculture & fishing | 2023 |
| Seahaven Care Ltd | Administrative & support | 2024 |
| Seahaven Pride Limited | Arts & recreation | 2021 |
| Seashore and More Ltd | Real estate | 2022 |
| Seaside Mini Market Eastbourne Ltd | Wholesale & retail | 2026 |
| Secnology Limited | Information & communication | 2017 |
| Second GEN Limited | Professional & scientific | 2020 |
| Sector Tech Solutions Ltd | Information & communication | 2024 |
| Select Trucks Ltd | Wholesale & retail | 2021 |
| Sellingmachine Ltd | Information & communication | 2020 |
| Senlac Specialist Works Ltd | Construction | 2019 |
| Sentia Prae Ltd | Information & communication | 2018 |
| Seraud Ltd | Wholesale & retail | 2014 |
| Serenata Developments Limited | Real estate | 2014 |
| Serenity Nature Community Interest Company | Arts & recreation | 2023 |
| Seriously Sorted Limited | Manufacturing | 2010 |
| Setrade Ltd | Wholesale & retail | 2013 |
| SEV Care Ltd | Extraterritorial | 2018 |
| SEX and Love Addiction Clinic Ltd | Health & social care | 2010 |
| Shepherds Huts Elite Limited | Wholesale & retail | 2014 |
| Sherborne Court (Eastbourne) Management Company Limited | Households | 1972 |
| Sherlock Heating Ltd | Construction | 2021 |
| Shift ALT Delete Limited | Information & communication | 2006 |
| Shining Light Productions Limited | Information & communication | 1999 |
| Shmc Enterprises Limited | Real estate | 2023 |
| Shores Ltd | Wholesale & retail | 2004 |
| Shoulders Leisure Limited | Hospitality | 2005 |
| Shree PDP Ltd | Information & communication | 2009 |