| Sea Architecture Limited | Professional & scientific | 2026 |
| Sea Road (Rustington) Management Limited | Households | 1996 |
| Seafields Management Company Limited | Households | 1988 |
| Seagate Court Management Company Limited | Households | 1983 |
| Seaspace VR Ltd | Information & communication | 2023 |
| Securecharm Property Management Limited | Households | 2000 |
| Selsey Court Residents Company Limited | Households | 2002 |
| Sendiplay Sensory Ltd | Education | 2025 |
| Setonhill Storage Facility Limited | Energy | 2022 |
| SEW Ethical Limited | Wholesale & retail | 2023 |
| Silly Goose Ltd | Manufacturing | 2025 |
| Sillywater Ltd | Health & social care | 2018 |
| Silversands Court Management Limited | Households | 2004 |
| Simplified Ideas Limited | Information & communication | 2023 |
| Simply Melted Ltd | Wholesale & retail | 2023 |
| Sistaland Ltd | Information & communication | 2025 |
| Skyline Blinds Ltd | Wholesale & retail | 2026 |
| Slindon Cinema Limited | Information & communication | 2025 |
| Slindon College Limited | Education | 1993 |
| Slinsted Capital Ltd | Financial services | 2026 |
| SLR Consult Limited | Health & social care | 2012 |
| Snuggled Contented Geese Ltd | Arts & recreation | 2024 |
| Social Impact Radio CIC | Information & communication | 2025 |
| Sognarf Limited | Real estate | 1959 |
| Soil Moisture Retention Somelco Limited | Agriculture & fishing | 2015 |
| Sonnet Group Ltd | Administrative & support | 2019 |
| Soul Dog Studios Ltd | Professional & scientific | 2024 |
| South Downs View Management Company Limited | Households | 2025 |
| South Plean Storage Facility Limited | Energy | 2023 |
| South Point Freehold Company Limited | Households | 2022 |
| Southdown Court Management (Southampton) Limited | Households | 2002 |
| Southdownscarpets Ltd | Construction | 2026 |
| Southern Counties Liming Limited | Agriculture & fishing | 2011 |
| Southern ID Solutions Limited | Administrative & support | 2003 |
| SOW Chic Limited | Wholesale & retail | 2024 |
| Specialist Business Services Limited | Professional & scientific | 2023 |
| Spot on Electrical Solutions Limited | Construction | 2018 |
| Sprint Electric Limited | Manufacturing | 1987 |
| Sprint Power Conversion Limited | Manufacturing | 2024 |
| Sprintroom Limited | Professional & scientific | 2012 |
| ST Georges Court (Chichester) Freehold Company Limited | Households | 2007 |
| ST. Mary at Clymping, Church Hall Co. Limited | Other services | 1985 |
| Stage Services Limited | Arts & recreation | 1994 |
| Steadways Limited | Financial services | 2011 |
| Steel the Blood of US CIC | Information & communication | 2024 |
| Storrington Management Company Limited | Households | 2013 |
| Strada Wheels Ltd | Manufacturing | 2010 |
| Strategic Corporate Resources Limited | Professional & scientific | 2015 |
| Strathmore Plants Ltd | Wholesale & retail | 2025 |
| Subud Britain | Other services | 1960 |
| Sudley Lodge Management Company Limited | Households | 1973 |
| Summer Breeze Cleaning Services Ltd | Administrative & support | 2026 |
| Summerfield Nurseries (Staple) Residents Management Company Ltd | Households | 2023 |
| Sunningdale Court Residents Association Limited | Households | 1962 |
| Sunnyboy Publishing Ltd | Information & communication | 2025 |
| Sunnyside RTM Company Limited | Households | 2004 |
| Supreme Motors Servicing and Repairs Ltd | Wholesale & retail | 2023 |
| Susila Dharma Britain | Health & social care | 1985 |
| Sussex County Landscaping Limited | Administrative & support | 2021 |
| Sussex Education Ltd | Education | 2023 |
| Sussex Farm Feeds Ltd | Manufacturing | 2025 |
| Sussex Film Office Ltd | Information & communication | 2016 |
| Sussex Fire and Oak Limited | Manufacturing | 2021 |
| Sussex Home of Target Shooting Limited | Arts & recreation | 2020 |
| Sussex Jams and Chutneys Ltd | Manufacturing | 2017 |
| Sussex Metal Art Limited | Manufacturing | 2026 |
| Sussex Mobility Limited | Arts & recreation | 1991 |
| Sussex Volunteer Fire and Rescue CIC | Public administration | 2023 |
| Suum Digital Limited | Information & communication | 2014 |
| Swanbourne Auto Works Ltd | Wholesale & retail | 2016 |
| Switchfab Limited | Real estate | 1989 |
| T. Hollister (Chertsey) Limited | Real estate | 1948 |
| Taigh Consulting Limited | Real estate | 2021 |
| Tarrant Street Consulting Ltd | Real estate | 2023 |
| Task Carpentry Ltd | Construction | 2019 |
| Tate at Home. Limited | Wholesale & retail | 2024 |
| Tays Engineering Ltd | Professional & scientific | 2019 |
| Tea and Biscuit Club LLP | | 2015 |
| Team Music Ltd | Manufacturing | 2007 |
| Technology Hire Service (UK) Ltd | Information & communication | 2011 |
| Tempcon Instrumentation Limited | Manufacturing | 1980 |
| Tetradock Ltd | Wholesale & retail | 2008 |
| THE A'Maize'Ing Feed Company Limited | Agriculture & fishing | 2005 |
| THE Amicus Community Arundel Limited | Health & social care | 2004 |
| THE Arundel Champagne House Limited | Wholesale & retail | 2018 |
| THE Blue House (Chichester) RTM Company Limited | Households | 2019 |
| THE Boss Stylist Academy Ltd | Professional & scientific | 2026 |
| THE Boxgrove Clinic LLP | | 2016 |
| THE Community Playcentre @ Walberton | Education | 2011 |
| THE Convenient Chef Ltd | Hospitality | 2024 |
| THE Dalby Group Ltd | Wholesale & retail | 2020 |
| THE Dedicated Gym Ltd | Other services | 2025 |
| THE Emplace Ltd | Professional & scientific | 2014 |
| THE Filmworkers Limited | Information & communication | 2023 |
| THE Grange (Westhampnett) Management Limited | Households | 2008 |
| THE Hedgerows (Plumpton Green) Residents Management Company Ltd | Households | 2025 |
| THE Ivory & Leather Limited | Manufacturing | 2025 |
| THE Landscape Library Limited | Other services | 2019 |
| THE Magic Marketer Ltd | Professional & scientific | 2026 |
| THE Magpie & Phoenix Nest Ltd | Real estate | 2026 |