| Sherman Stores Sussex Limited | Wholesale & retail | 2003 |
| Sherman Sussex Ltd | Wholesale & retail | 2009 |
| Sheviocke Property Limited | Real estate | 2020 |
| SHG Materials Ltd | Construction | 2026 |
| SHH Event Services Limited | Administrative & support | 2013 |
| Shift.Buzz Ltd | Professional & scientific | 2026 |
| Shilla Retreat and Care Support Services Ltd | Health & social care | 2026 |
| Shine on the Green Limited | Other services | 2008 |
| Ship & Anchor Marina Limited(The) | Hospitality | 1965 |
| Shipleyworld Limited | Extraterritorial | 2007 |
| Shipserv Limited | Transport & logistics | 2000 |
| Shipshape General Services Limited | Administrative & support | 1995 |
| Shirwan Enterprise Limited | Wholesale & retail | 2022 |
| SHISHCO47 Ltd | Hospitality | 2026 |
| Shoot From the HIP LLP | | 2023 |
| Shoot to Kill Films Ltd | Information & communication | 2018 |
| Shooting Field 1968 Limited | Financial services | 2014 |
| Shop Malo Ltd | Wholesale & retail | 2019 |
| SHOP4AUTOPARTS Ltd | Wholesale & retail | 2017 |
| Shopshop Ltd | Construction | 2014 |
| Shopthru Limited | Information & communication | 2016 |
| Shore Property Management Ltd | Real estate | 2023 |
| Shoreham Fireplace Centre Limited | Wholesale & retail | 2003 |
| Shoreline Carpentry Limited | Construction | 2018 |
| Shoreline Enterprises Ltd | Education | 2016 |
| Shoreline Plumbing, Heating & GAS Limited | Construction | 2017 |
| Short Street Finance Ltd | Professional & scientific | 2022 |
| Short Street Productions Limited | Arts & recreation | 2022 |
| Shortie Bear 1981 Ltd | Wholesale & retail | 2023 |
| Shout Web Solutions Ltd | Information & communication | 2017 |
| Show Production Services Limited | Administrative & support | 2012 |
| Showlargerglobalservices Ltd | Wholesale & retail | 2025 |
| Shreejee News Limited | Wholesale & retail | 2014 |
| Shripney Management Ltd | Professional & scientific | 2024 |
| Shuffle Fitness Limited | Wholesale & retail | 2021 |
| Shukar Calton Properties Limited | Real estate | 2022 |
| Shutters of Sussex Ltd | Wholesale & retail | 2021 |
| SHY Panda Ltd | Wholesale & retail | 2023 |
| SIA Automotive Limited | Administrative & support | 2014 |
| SIA Aviation Limited | Transport & logistics | 2013 |
| Sian Farley Productions Ltd | Arts & recreation | 2015 |
| Sick Bicycle Co. Limited | Manufacturing | 2017 |
| Side Quest Media Ltd | Information & communication | 2023 |
| Sidecar Tech Consulting Limited | Information & communication | 2024 |
| Sidecase Limited | Households | 1991 |
| Sidemen Clothing Limited | Wholesale & retail | 2014 |
| Sidemen Entertainment Limited | Information & communication | 2019 |
| Sidemen Holdings Limited | Financial services | 2019 |
| Sidemen Productions Limited | Information & communication | 2022 |
| Sidemen Project 1 Limited | Wholesale & retail | 2023 |
| Sidemen Ventures Limited | Administrative & support | 2021 |
| Sierra Solutions Limited | Professional & scientific | 2017 |
| Sifleet Services Ltd | Hospitality | 2025 |
| Sight Support Worthing | Other services | 1999 |
| Sigma Estates (Sussex) Limited | Extraterritorial | 2009 |
| Sigma Estates Limited | Construction | 1994 |
| Sigrid Media Ltd | Professional & scientific | 2024 |
| Sigva Decoration Ltd | Construction | 2020 |
| Sigva Maintenance Ltd | Real estate | 2025 |
| Sigva Properties Ltd | Real estate | 2022 |
| Siilo Limited | Real estate | 2020 |
| Silk Purse Ltd | Wholesale & retail | 2010 |
| Sillman Thomas Limited | Administrative & support | 2012 |
| Silphi LLP | | 2014 |
| Silver Appleyard Productions Limited | Arts & recreation | 1997 |
| Silver FOX Management Services Limited | Professional & scientific | 2019 |
| Silver Kravitz Limited | Real estate | 2002 |
| Silver Stag Digital Ltd | Information & communication | 2015 |
| Silver Wala Ltd | Information & communication | 2020 |
| Silverdale Estate Management Limited | Administrative & support | 2002 |
| Silverlake Services Ltd | Professional & scientific | 2024 |
| Silverlea Consultancy Limited | Professional & scientific | 2014 |
| Silverleaf Ventures Limited | Financial services | 2025 |
| Silverline Construction Limited | Construction | 2015 |
| Silvi Trimmings Limited | Real estate | 1976 |
| SIM LAB Limited | Professional & scientific | 2015 |
| Simba Softworks Ltd | Information & communication | 2026 |
| Similan Trading Limited | Hospitality | 2003 |
| Simmonds and White Ltd | Hospitality | 2016 |
| Simmonds Property Holdings Limited | Real estate | 2017 |
| Simms Garage Limited | Wholesale & retail | 1980 |
| Simon and Prime Ltd | Professional & scientific | 2021 |
| Simon Bailey Development Ltd | Administrative & support | 2016 |
| Simon Fairman Ltd | Professional & scientific | 2016 |
| Simon Hyde Optical Ltd | Wholesale & retail | 2021 |
| Simon Manley Holdings Limited | Financial services | 2024 |
| Simon Tappin Ltd | Arts & recreation | 2014 |
| Simon Thom Ltd | Hospitality | 2015 |
| Simon Wiggins Cars Limited | Wholesale & retail | 2015 |
| Simple Signs Limited | Manufacturing | 2025 |
| Simply Aesthetics UK Limited | Other services | 2009 |
| Simply Glow Ltd | Manufacturing | 2025 |
| Simply Pondz Limited | Agriculture & fishing | 2018 |
| Simply Professional Limited | Information & communication | 1988 |
| Simply Smarter Marketing Limited | Professional & scientific | 2009 |
| Simplyathletic Limited | Other services | 2024 |
| SIN City Inc Ltd | Construction | 2015 |
| Sinbad Tech Ltd | Administrative & support | 2009 |
| Sinchets Ltd | Real estate | 2022 |
| Sirc Productions Limited | Information & communication | 2026 |