| Sefm Ltd | Real estate | 2023 |
| Seits Ltd | Information & communication | 2025 |
| Selbourne Residential Limited | Real estate | 2020 |
| Selden B&B Ltd | Hospitality | 2016 |
| Selden Court Management Company Limited | Households | 2020 |
| Selden Farm Ltd | Agriculture & fishing | 2008 |
| Selden FOX Ltd | Administrative & support | 2010 |
| Selden Management Ltd | Other services | 2009 |
| Selden Vineyard Ltd | Agriculture & fishing | 2024 |
| Selection 971 Ltd | Wholesale & retail | 2025 |
| Self-Care Resources Ltd | Information & communication | 2020 |
| Selia Worthing Ltd | Hospitality | 2023 |
| SEM Media Limited | Information & communication | 2023 |
| Semaco Limited | Professional & scientific | 2001 |
| Semper Prima Homes Ltd | Real estate | 2025 |
| Semypolky Solar Limited | Financial services | 2019 |
| SEN Mobile Hairdressing Ltd | Other services | 2020 |
| Send Investments Limited | Real estate | 1992 |
| Sendit Group (Sussex) Ltd | Construction | 2022 |
| Sensis Cleaning Limited | Administrative & support | 2020 |
| Sensory Cottage Limited | Education | 2022 |
| Sententia ERP Limited | Information & communication | 2016 |
| Senter Properties Limited | Financial services | 2021 |
| Sequel Financial Planning UK Ltd | Professional & scientific | 2020 |
| SER Costs Solutions Limited | Professional & scientific | 2011 |
| Seren FÔR LLP | | 2025 |
| Serena Mansions Limited | Households | 1964 |
| Serene Bathrooms Ltd | Construction | 2019 |
| Serene Soul Alchemy - by Anca Pinciuc Ltd | Manufacturing | 2025 |
| Serenity Accounting Services Ltd | Professional & scientific | 2020 |
| Serenity IT (Essex) Limited | Professional & scientific | 2018 |
| Serious Journalism Ltd | Information & communication | 2026 |
| Serpeus Limited | Households | 1976 |
| Serraq HQ Limited | Financial services | 2017 |
| Setpoint Consulting Limited | Professional & scientific | 2012 |
| Sett Ventures Limited | Professional & scientific | 2011 |
| Sevali Ltd | Hospitality | 2019 |
| Seven Dials Media Limited | Professional & scientific | 2022 |
| Seven M&E (7PG) Ltd | Construction | 2023 |
| Seven Plus Beauty Ltd | Other services | 2017 |
| Seven Properties Group Ltd | Construction | 2023 |
| Seven Property Development Ltd | Construction | 2022 |
| Seven Saas Limited | Information & communication | 2025 |
| Seven Selden Road (Worthing) Limited | Households | 2021 |
| Seven SIX Fourteen Ltd | Real estate | 2021 |
| Seven Valleys Consulting Limited | Professional & scientific | 2023 |
| Sevenfiguremedia LLP | | 2019 |
| Seventeen Miles Limited | Professional & scientific | 2023 |
| Severnside Carbon Capture and Shipping Hub Ltd | Construction | 2022 |
| SEW Lazy London Ltd | Wholesale & retail | 2022 |
| SEW Silver Limited | Wholesale & retail | 2007 |
| Seward Limited | Manufacturing | 1996 |
| SF Amanat Property Ltd | Real estate | 2026 |
| SF Quality Solutions Limited | Other services | 2020 |
| Sfakion Developments Limited | Information & communication | 2019 |
| Sfdi Ltd | Public administration | 2026 |
| SFE Consultancy Ltd | Professional & scientific | 2021 |
| SFO Capital Limited | Financial services | 2020 |
| SFO Capital Partners Limited | Financial services | 2019 |
| SG Properties Investment Ltd | Real estate | 2024 |
| SGI Research Ltd | Professional & scientific | 2025 |
| SGM Engineering Consultancy Ltd | Professional & scientific | 2023 |
| SGM Properties Ltd | Construction | 2025 |
| SGS Flying Services Limited | Professional & scientific | 2019 |
| SGS Splashbacks Limited | Construction | 2020 |
| Shabern Property Limited | Real estate | 1991 |
| Shade Hair Limited | Other services | 2025 |
| Shafiques Holdings Ltd | Hospitality | 2017 |
| Shahidy Ltd | Hospitality | 2025 |
| Shake IT UP Creative Ltd | Information & communication | 2015 |
| Shake Properties Limited | Real estate | 2021 |
| Shaken & Stirred On-Site Ltd | Hospitality | 2025 |
| Shallow-Sea Consultancy Ltd | Information & communication | 2025 |
| Shamdar Ltd | Wholesale & retail | 2026 |
| Shammah Ltd | Real estate | 2022 |
| Shamo Burger Ltd | Hospitality | 2026 |
| Shanakee Creations Limited | Information & communication | 2013 |
| Shannon Personnel Services Limited | Real estate | 1978 |
| SHARE3 Limited | Information & communication | 2024 |
| Sharkmove Ltd | Transport & logistics | 2020 |
| Sharp Edge Investments Limited | Real estate | 2019 |
| Sharp Padel Limited | Wholesale & retail | 2025 |
| Sharp Shipping Limited | Transport & logistics | 2000 |
| Sharpines Ltd | Health & social care | 2026 |
| Sharpish Ltd | Administrative & support | 2022 |
| Sharu Brothers Ltd | Hospitality | 2020 |
| Sharu Ltd | Wholesale & retail | 2017 |
| Shaunz Ltd | Other services | 2019 |
| Shaw Spray Ltd | Construction | 2020 |
| Shaws Installations Limited | Construction | 1998 |
| Shaws of Brighton Limited | Construction | 1995 |
| Sheephouse Holdings Ltd | Financial services | 2022 |
| Sheff Plumbing & Heating Limited | Construction | 2014 |
| Sheila M Limited | Professional & scientific | 2012 |
| Shelley House (Worthing) Limited | Real estate | 2017 |
| Shemis Consulting Limited | Information & communication | 2013 |
| Shemis Estates Limited | Real estate | 2020 |
| Shenmoor Limited | Households | 2002 |
| Sherbet Dabbie Ltd | Transport & logistics | 2023 |
| Sherlock and Clark Limited | Construction | 2018 |