| Samphire Group Holdings Ltd | Financial services | 2021 |
| Sampy’S Cafe Ltd | Hospitality | 2025 |
| Sanders Shiers Limited | Information & communication | 2007 |
| Sanders Studios EOT Ltd | Professional & scientific | 2022 |
| Sangar Ltd | Administrative & support | 2010 |
| Scaffolding Cornwall Ltd | Construction | 2022 |
| Scamp's Bulbs Ltd | Wholesale & retail | 2025 |
| Scarlet Wines Falmouth Ltd | Wholesale & retail | 2025 |
| Scary Little Girls Association CIC | Health & social care | 2019 |
| Science Stories Limited | Information & communication | 2018 |
| Scooter Works Europe Ltd | Wholesale & retail | 2012 |
| Scope Loans Ltd | Financial services | 2025 |
| Scope Property Developments Limited | Construction | 2024 |
| Scrace & Company Limited | Construction | 2004 |
| Sea and Saffron Limited | Real estate | 2025 |
| Sea Kayaking Cornwall Ltd | Arts & recreation | 2007 |
| Sea-Cubed Ltd | Manufacturing | 2004 |
| Seack Construction Limited | Construction | 2014 |
| Seack Developments Ltd | Construction | 2018 |
| Seack Management Ltd | Households | 2019 |
| Seaforge Synergy Consulting Ltd | Professional & scientific | 2025 |
| Sealect Coatings Ltd | Manufacturing | 2015 |
| Search Natural Ltd | Information & communication | 2019 |
| Seasalt Holdings Limited | Wholesale & retail | 2002 |
| Seasalt Limited | Wholesale & retail | 1988 |
| Seasentry Ltd | Professional & scientific | 2010 |
| Seaweed Generation Ltd | Agriculture & fishing | 2021 |
| Selby & Mills Limited | Administrative & support | 2000 |
| Sellectronics Limited | Manufacturing | 2010 |
| Sellerdash Ltd | Wholesale & retail | 2023 |
| Seloc Limited | Other services | 2003 |
| Semore Seismic Limited | Administrative & support | 2002 |
| Sennara Limited | Other services | 2024 |
| Seth Baccus Guitars Ltd | Manufacturing | 2018 |
| Seventh Wave Developments Ltd | Real estate | 2018 |
| Shark Bytes Limited | Information & communication | 2026 |
| Shaun Harvey Mortgages Ltd | Financial services | 2020 |
| Shaws Reach Developments Limited | Construction | 2018 |
| Shea & Co. Property Ltd | Real estate | 2026 |
| Shinelight Limited | Real estate | 1986 |
| Shipbrook Ltd | Wholesale & retail | 2022 |
| Shoreside Rigging Ltd | Manufacturing | 2023 |
| Shyman Limited | Extraterritorial | 2009 |
| Sian Roper Creative Ltd | Professional & scientific | 2019 |
| Sias Origin Limited | Transport & logistics | 2017 |
| Siddhashram Limited | Hospitality | 2025 |
| Signal North Ltd | Information & communication | 2025 |
| Silicon Pasty Ltd | Information & communication | 2024 |
| Silus Limited | Information & communication | 2021 |
| Simon Spear Ltd | Professional & scientific | 2016 |
| Sintija & Co. Limited | Health & social care | 2009 |
| Skentel Limited | Professional & scientific | 2014 |
| Sky Light Cinemas Limited | Information & communication | 2016 |
| Slbf Geoscience Ltd | Professional & scientific | 2022 |
| Small Ships Ltd | Hospitality | 2018 |
| Smart CUT South West Limited | Administrative & support | 2010 |
| Smart Electrical SW Ltd | Construction | 2024 |
| Smash Developments Limited | Construction | 2010 |
| Smith and Chinn Limited | Construction | 2019 |
| Smith Devey Holdings Limited | Financial services | 2026 |
| Smith Devey Property Limited | Hospitality | 2022 |
| Smithick Cars Limited | Transport & logistics | 2025 |
| Smokin BBQ Falmouth Limited | Hospitality | 2024 |
| SO Clean Windows Limited | Administrative & support | 2005 |
| Social Designs C.I.C. | Construction | 2021 |
| SOL Wave Ltd | Arts & recreation | 2025 |
| Sol's Plumbing Heating Renewables Ltd | Construction | 2024 |
| Solar Asset Management Ltd | Administrative & support | 2017 |
| Sorted Bricks Ltd | Professional & scientific | 2026 |
| Soup Audiovisual Ltd | Information & communication | 2025 |
| South West CPM Limited | Real estate | 2025 |
| South West Enterprises LLP | | 2015 |
| South West Marine Electrical Services Ltd | Construction | 2018 |
| South West Pipeworks Limited | Manufacturing | 2014 |
| South West Prop Limited | Real estate | 2017 |
| Southern Pacific (UK) Limited | Wholesale & retail | 2005 |
| Southwest Mortgages Ltd | Financial services | 2019 |
| Spaceship Audio Limited | Manufacturing | 2016 |
| Sparten Limited | Financial services | 2017 |
| Spec-Co Ltd | Wholesale & retail | 2024 |
| Speed Marine Ltd | Transport & logistics | 2012 |
| Spencer-Carter (Properties) Limited | Real estate | 1964 |
| Spencer-Carter Estates Limited | Professional & scientific | 2008 |
| Spencer-Carter Holdings Limited | Professional & scientific | 2008 |
| Spiralis Plants Ltd | Wholesale & retail | 2018 |
| SPJ Finance and Accountancy Services Ltd | Professional & scientific | 2023 |
| Splann Build Ltd | Construction | 2022 |
| Splendour Rock Ltd | Professional & scientific | 2024 |
| SPM of Cornwall Ltd | Construction | 2023 |
| Spotbeam Communications Limited | Information & communication | 2000 |
| Springside Services Limited | Professional & scientific | 1963 |
| Squeaky Clean Cornwall Ltd | Administrative & support | 2021 |
| Sruth-Cuan Limited | Information & communication | 2015 |
| ST Michael's Crew Limited | Administrative & support | 2017 |
| ST Michael's Falmouth Limited | Hospitality | 2016 |
| ST. Mawes Garage Limited | Other services | 1975 |
| Stand UP Paddle Co Ltd | Arts & recreation | 2022 |
| Star Glazers Ltd | Wholesale & retail | 2021 |
| Starlight Yachts Limited | Manufacturing | 2001 |
| Station Road Enterprises Limited | Real estate | 1996 |