| Southern Interior Solutions Ltd | Construction | 2018 |
| Southern Shutters UK Specialists Ltd | Wholesale & retail | 2012 |
| Southfield Structural Services Limited | Manufacturing | 2009 |
| Southgate Chichester Limited | Health & social care | 2016 |
| Southlands Fire and Electrical Ltd | Construction | 2024 |
| Southsea Flatlets Limited | Real estate | 1964 |
| Southsea Games Gurus Limited | Other services | 2016 |
| SP Group (London) Ltd | Professional & scientific | 2019 |
| Spare 641 Limited | Wholesale & retail | 2016 |
| Spare 657 Ltd | Financial services | 2024 |
| Spark Power Ltd | Manufacturing | 2011 |
| Spark TV Ltd | Information & communication | 2016 |
| Sparrow Carpentry Ltd | Manufacturing | 2023 |
| Sparxx Electrical Ltd | Construction | 2019 |
| Speak Together Ltd | Professional & scientific | 2019 |
| Specialist Mortgage Services Limited | Financial services | 2021 |
| Spectrum Painting and Decorating Services Ltd | Construction | 2020 |
| Speed Chaser Ltd | Manufacturing | 2024 |
| Speed Track Toy Limited | Wholesale & retail | 2017 |
| Spencer Swaffer Antiques Limited | Wholesale & retail | 2003 |
| Spences Spokes Limited | Wholesale & retail | 2024 |
| SPG Chemical Engineering Consulting Limited | Professional & scientific | 2024 |
| Spiced Sussex Ltd | Wholesale & retail | 2021 |
| Spicy Finance Ltd | Professional & scientific | 2016 |
| Spinnaker Support Limited | Professional & scientific | 2008 |
| Spinney (Management) Limited | Real estate | 1961 |
| Spinneys Grange Consulting Ltd | Professional & scientific | 2021 |
| Spinning Medal Ltd | Wholesale & retail | 2024 |
| Spire Carpentry & Construction Ltd | Construction | 2023 |
| Spire Homes Management Company Limited | Households | 2018 |
| Spire Metals Limited | Water & waste | 2014 |
| Spitfire Building Company Limited | Real estate | 2021 |
| Spitfiresdotcom Ltd | Education | 2021 |
| SPJ Holdings Ltd | Financial services | 2020 |
| SPJ Properties (Sussex) Ltd | Real estate | 2020 |
| Splashrobe Limited | Wholesale & retail | 2021 |
| Splits Bakery Limited | Wholesale & retail | 2008 |
| SPN Holdco Ltd | Administrative & support | 2021 |
| SPO Atelier Limited | Information & communication | 2026 |
| Sportair Ltd | Administrative & support | 2014 |
| Sports and Design Ltd | Wholesale & retail | 2011 |
| Sports Data Modelling Limited | Information & communication | 2020 |
| Sports Dream | Arts & recreation | 2010 |
| Sportslife Academy Ltd | Arts & recreation | 2014 |
| Sportsrapt Limited | Manufacturing | 2026 |
| Spot on Theatre Productions Ltd | Arts & recreation | 2002 |
| Spread Eagle Group Ltd | Real estate | 2019 |
| Spread Eagle Trading Ltd | Real estate | 2019 |
| Spritz Wellness Limited | Manufacturing | 2017 |
| Sproggle Ltd | Administrative & support | 2026 |
| Spur Garage (Slindon) Limited | Wholesale & retail | 1998 |
| Squadron Business Consulting Ltd | Professional & scientific | 2018 |
| Square Dining EV Limited | Hospitality | 2026 |
| Square Scaffolding Solutions Ltd | Construction | 2023 |
| Squirrel Commercials Ltd | Wholesale & retail | 2024 |
| Squirrels DEN Daycare Ltd | Health & social care | 2023 |
| Squirrels Reach Management Company Limited | Households | 1996 |
| SR Private Ltd | Wholesale & retail | 2022 |
| SRB Investments Limited | Professional & scientific | 2019 |
| SRE Consulting Limited | Professional & scientific | 2012 |
| SRI Lanka Build Ltd | Construction | 2016 |
| SRM Couriers Ltd | Transport & logistics | 2022 |
| SRP Design and Print Limited | Manufacturing | 2013 |
| SS2 Advisory Ltd | Professional & scientific | 2019 |
| ST Georges Court (Donnington ) Estate Management Limited | Administrative & support | 2014 |
| ST Georges Gardens (Worthing) Freehold Ltd | Households | 2012 |
| ST James Carpentry and Construction Limited | Construction | 2025 |
| ST Johns House Accounting Limited | Professional & scientific | 2020 |
| ST Mental Health Ltd | Health & social care | 2025 |
| ST Michael's Lodge (Worthing) Limited | Households | 2001 |
| ST Olav Trust | Wholesale & retail | 2008 |
| ST Pancras Chambers Limited | Construction | 2024 |
| ST Richard of Chichester Christian Care Association Ltd. | Health & social care | 1990 |
| ST Wilfrids Hospice Trading Limited | Wholesale & retail | 1987 |
| ST. Botolphs Service Management Limited | Households | 1997 |
| ST. John's Street Tenants Limited | Households | 1974 |
| ST. Joseph's Estate Management Company Limited | Households | 2002 |
| ST. Lawrence Court Management Company (Worthing) Ltd. | Households | 2008 |
| ST. Paul's Gardens Management Company Limited | Administrative & support | 1986 |
| ST. Wilfrid's Hospice (South Coast) Limited | Health & social care | 1981 |
| Stable Antiques Limited | Wholesale & retail | 2004 |
| Stac Climate Control Limited | Construction | 2012 |
| Stac Projects Ltd | Construction | 2020 |
| Stafford Haulage Limited | Transport & logistics | 2015 |
| Stalwart Building Innovations Limited | Construction | 2025 |
| Stampede UK Limited | Real estate | 2005 |
| Standcourt Limited | Real estate | 2000 |
| Standen Accounting & Bookkeeping Limited | Professional & scientific | 2023 |
| Standout Finance Limited | Extraterritorial | 2024 |
| Standout Legal Limited | Extraterritorial | 2024 |
| Standout Social Media Limited | Extraterritorial | 2024 |
| Stanford Training Solutions Ltd | Education | 2014 |
| Stanley Ball Limited | Real estate | 1961 |
| Star Advertising Products Limited | Agriculture & fishing | 2003 |
| Star Physiotherapy Community Interest Company | Health & social care | 2017 |
| Starfish AP Ltd | Professional & scientific | 2026 |
| Starfleet Software Limited | Information & communication | 2018 |
| Starline Group Holdings Limited | Professional & scientific | 2018 |
| Starline Private Hire Limited | Transport & logistics | 2018 |
| Starline Sussex Limited | Transport & logistics | 2012 |