| Special Partnership Trust | Education | 2011 |
| Special Project SIX Ltd | Information & communication | 2015 |
| Specialist Stonemasonry Ltd | Construction | 2014 |
| Spectrum Tailored Technologies Ltd | Information & communication | 2022 |
| Spinnakers Valley Road (2) Management Company Limited | Households | 2007 |
| Spinnakers Valley Road Management Company Limited | Households | 2006 |
| Spiral Construction Holdings Limited | Financial services | 2019 |
| Spiral Construction Limited | Construction | 1985 |
| Spiral Construction Properties Limited | Real estate | 2019 |
| Spiritus Consulting Limited | Professional & scientific | 1994 |
| Spiritus Group Limited | Professional & scientific | 2001 |
| Splann Productions Ltd | Information & communication | 2018 |
| Sports Land Solutions Ltd | Professional & scientific | 2019 |
| Spotless Cleaning Cornwall Limited | Administrative & support | 2018 |
| Springfield Court (ST Mary's) Limited | Households | 1971 |
| Springle Photography Limited | Professional & scientific | 2015 |
| SQUARE13 Limited | Administrative & support | 2018 |
| Squid Hosting Ltd | Information & communication | 2022 |
| SSR Properties Truro LLP | | 2024 |
| ST Austell Urban Village Management Company Limited | Households | 2002 |
| ST EIA Apartments Property Management Company Limited | Extraterritorial | 2018 |
| ST EIA Townhouses Property Management Company Limited | Extraterritorial | 2018 |
| ST Erme Medical Limited | Health & social care | 2019 |
| ST EWE Agriculture Limited | Agriculture & fishing | 2026 |
| ST EWE Fine Foods Limited | Manufacturing | 2025 |
| ST EWE Free Range Eggs (Trading) LLP | | 2012 |
| ST EWE Free Range Eggs Limited | Wholesale & retail | 2018 |
| ST Ives School of Glass Bead Making Limited | Manufacturing | 2017 |
| ST Ives WS CIC | Real estate | 2018 |
| ST Johns Close (Management Company) Limited | Real estate | 2025 |
| ST Martin's Holdings Ltd. | Real estate | 2015 |
| ST Martin's Minerals Ltd. | Construction | 2013 |
| ST Martins Campsite Limited | Hospitality | 2022 |
| ST Mawes Cottages Limited | Real estate | 2023 |
| ST Mawes Dental Ltd | Health & social care | 2017 |
| ST Mawes Ferry Company Limited | Extraterritorial | 2003 |
| ST Michael's Croft Limited | Construction | 2013 |
| ST Michael's Stracey Road Limited | Construction | 2013 |
| ST Moritz (Holdings) Limited | Financial services | 2012 |
| ST Moritz Enterprises Limited | Extraterritorial | 2012 |
| ST Petrocs | Hospitality | 2019 |
| ST Pirans Court (Pengegon) Limited | Households | 2008 |
| ST Rumon's Parc Management Company Limited | Households | 2016 |
| ST Stephens Court Management Co Ltd | Hospitality | 2015 |
| ST. Agnes Management Company Limited | Households | 1990 |
| ST. Clements Vean Management Company Limited | Households | 1998 |
| ST. Erme Playing Fields Limited | Wholesale & retail | 2011 |
| ST. Mawes Sailing Club Ltd | Arts & recreation | 2013 |
| Stackrflow Ltd | Information & communication | 2026 |
| Stallards Events Limited | Professional & scientific | 2023 |
| Standens (Truro) Limited | Wholesale & retail | 2014 |
| Stanley Court Bodmin Limited | Households | 2006 |
| Stargazey Ltd | Hospitality | 2023 |
| Starlene.To Limited | Wholesale & retail | 2026 |
| Starling Close Residents Association Limited | Households | 2022 |
| Starr Financial Planning Ltd | Financial services | 2015 |
| Stars and Embers Glamping Limited | Hospitality | 2019 |
| Statio Ltd | Professional & scientific | 2014 |
| Stayathome Limited | Administrative & support | 2005 |
| Steel Magnolias NQY Ltd | Wholesale & retail | 2022 |
| Stephens & Stephens Developers (Cliffedge 10) Ltd | Construction | 2022 |
| Stephens & Stephens Developers (Grampound) Ltd | Construction | 2022 |
| Stephens & Stephens Developers (NO1 Pentire) Ltd | Construction | 2022 |
| Stephens & Stephens Developers (Seaton) Ltd | Construction | 2022 |
| Stephens & Stephens Property Management Ltd | Households | 2020 |
| Stephens Enterprises Ltd | Real estate | 2006 |
| Stephens Scown Secretarial Limited | Extraterritorial | 1988 |
| Stephenson Commercial Investments Limited | Real estate | 2005 |
| Stephenson Regeneration Ltd | Real estate | 2016 |
| Steppi UK Limited | Information & communication | 2024 |
| Sterna Limited | Health & social care | 1999 |
| Steve Gray & Sons Ltd | Construction | 2007 |
| Steve Jenkin Plumbing Ltd | Construction | 2016 |
| Steve's Carpentry & Joinery Limited | Construction | 2003 |
| Stillerz Ltd | Hospitality | 2025 |
| Stillness in the Storms Ltd | Information & communication | 2024 |
| Stir Cornwall Limited | Real estate | 2020 |
| Stirland Transportation Ltd | Transport & logistics | 2024 |
| Stitched & Stuffed Limited | Other services | 2019 |
| Stobbs Scaffolding Ltd | Construction | 2023 |
| Stone and Tide Ltd | Construction | 2025 |
| Stoproll Ltd | Manufacturing | 2022 |
| Storage South West Ltd | Transport & logistics | 2023 |
| Storage Truro LLP | | 2023 |
| Storeyline Leadership Limited | Professional & scientific | 2025 |
| Storm Force Films Limited | Information & communication | 2014 |
| Stowerwell Developments Limited | | 1988 |
| Strangways Terrace Residents Association Limited | Households | 1987 |
| Stratagems UN Limited | Real estate | 2014 |
| Stratton Carpentry Ltd | Manufacturing | 2021 |
| Strawberry Rose Cornwall Ltd | Wholesale & retail | 2019 |
| Streamclare Limited | Real estate | 1963 |
| Stronghold Alarm Systems Limited | Administrative & support | 2020 |
| Stuart Pritchard Properties Ltd | Real estate | 2025 |
| Student Direction Limited | Education | 2012 |
| Student Stretch Ltd | Wholesale & retail | 2020 |
| Studio Agni Ltd | Manufacturing | 2024 |
| Studio DM Limited | Professional & scientific | 2015 |
| Studio FAR West Ltd | Professional & scientific | 2022 |
| Studio Pond Ltd | Professional & scientific | 2017 |