| Shah Cabs Ltd | Transport & logistics | 2019 |
| Shawsafe Fire Safety Ltd | Professional & scientific | 2019 |
| Shea Alchemy Ltd | Wholesale & retail | 2007 |
| Shell Like EAR Care Limited | Health & social care | 2025 |
| Sheriffhales Solar Community Interest Company | Energy | 2015 |
| Shiney Electrical Ltd | Construction | 2023 |
| Shining Stars Residential Ltd | Health & social care | 2025 |
| Shore Asset Finance Limited | Administrative & support | 2024 |
| Sillian Holdings Limited | Financial services | 2024 |
| Simex Enterprises Limited | Administrative & support | 2022 |
| Simex Properties Limited | Real estate | 2018 |
| Simon Harris Trees and Grounds Limited | Administrative & support | 1998 |
| Simply Payroll (SW) Limited | Professional & scientific | 2011 |
| Simply Solutions Legal and Accountancy Services Ltd | Professional & scientific | 2019 |
| Sisley's & Crellow Ltd | Manufacturing | 2015 |
| SJ Andrew & Sons Limited | Wholesale & retail | 2009 |
| SJ Andrew Holdings Limited | Professional & scientific | 2010 |
| SJM Marketing Ltd | Financial services | 2025 |
| Sjstrengthuk Limited | Arts & recreation | 2015 |
| SJT Events and Design Limited | Construction | 2015 |
| SK Offshore Consultancy Limited | Professional & scientific | 2023 |
| Skills Over School Ltd | Education | 2026 |
| Skills Over School Project CIC | Education | 2026 |
| Slapdash Studio Ltd | Construction | 2024 |
| Smart Drywall Systems Ltd | Construction | 2025 |
| Smart Group South West Limited | Financial services | 2014 |
| Smart Repairs (SW) Ltd | Other services | 2023 |
| SMB (SW) Ltd | Construction | 2021 |
| Smokey Joe's Cornwall Limited | Hospitality | 2005 |
| Socalm Birth Co. Ltd | Health & social care | 2019 |
| SOFTWARE4BIZ Ltd | Information & communication | 1985 |
| Soho House of Hair Ltd | Other services | 2024 |
| Solar Vehicle Access Ltd | Construction | 2006 |
| Sorlingas Data Services Limited | Information & communication | 2019 |
| Soronic Limited | | 1985 |
| Soul Elixir Ltd | Wholesale & retail | 2025 |
| Sous Chef Limited | Hospitality | 2024 |
| South Coast Fisheries Ltd | Agriculture & fishing | 2010 |
| South West AV Group Ltd | Financial services | 2020 |
| South West Door Company Ltd | Manufacturing | 2025 |
| South West Electrical Solutions Ltd | Construction | 2008 |
| South West Ventilation Ltd | Construction | 2013 |
| Southwest Air Brake Ltd. | Wholesale & retail | 2012 |
| Southwest Insulating Limited | Construction | 2024 |
| Southwest Performance Ltd | Wholesale & retail | 2021 |
| Sowena Cornwall CIC | Health & social care | 2023 |
| Sparkworthy Ltd | Construction | 2025 |
| Spider Bar Ltd | Hospitality | 2014 |
| Spinone Limited | Wholesale & retail | 2020 |
| Spittal Building Ltd | Construction | 2022 |
| Springfield Meadows Limited | Households | 2019 |
| SPS Architectural Services Limited | Professional & scientific | 2006 |
| ST Day Old Church Community Interest Company | Arts & recreation | 2016 |
| ST Day Parish Community Interest Company | Extraterritorial | 2023 |
| ST Day Tourist Park Ltd | Hospitality | 2016 |
| ST Elmo Property Management Company Ltd | Households | 2005 |
| ST Forecourt Limited | Wholesale & retail | 2013 |
| ST Pirans Way Shortlanesend Management Company Limited | Households | 2008 |
| Stamford Developments (Cornwall) Ltd | Construction | 2020 |
| Stanforth & Wicks Ltd | Construction | 2019 |
| Stanley Court (Parkham) Management Company Limited | Households | 2020 |
| Starling Motors Limited | Wholesale & retail | 2007 |
| Start Living for Today Ltd | Professional & scientific | 2019 |
| Startmake Enterprises Limited | Real estate | 1993 |
| Station Road ML Limited | Hospitality | 2024 |
| Stedi Arts Limited | Wholesale & retail | 2010 |
| Stellar Online Health Ltd | Wholesale & retail | 2018 |
| Stennack Homecare Limited | Health & social care | 2021 |
| Steve Benney Fire Risk Consulting Ltd | Financial services | 2017 |
| Steve Pritchard Electrical Limited | Construction | 2010 |
| Stillmere Limited | Professional & scientific | 2025 |
| Stitch Mental Health Access CIC | Health & social care | 2025 |
| Stithians Agricultural Association Limited | Administrative & support | 2011 |
| Stonecrop Properties Holdings Limited | Financial services | 2024 |
| Stonecrop Properties Limited | Real estate | 2024 |
| Stones Court (ST. Ives) RTM Company Limited | Households | 2009 |
| Studio 316 Limited | Information & communication | 2021 |
| Studio Bryony Ella Ltd | Arts & recreation | 2024 |
| Sublime Automotive Limited | Wholesale & retail | 2018 |
| Subsurface Dynamics Limited | Professional & scientific | 2024 |
| Sullivan Fire & Security Ltd | Construction | 2020 |
| Sun & Snow (Knightsbridge) Limited | Transport & logistics | 1990 |
| Sunnymead Projects Ltd | Construction | 2024 |
| Sunnyside Over Wharf Limited | Households | 1989 |
| Sunrise Cornwall CIC | Health & social care | 2024 |
| Sunshine Landscape Construction Ltd | Construction | 2020 |
| Sunwise Ltd | Real estate | 2019 |
| Superfast Schools Limited | Extraterritorial | 2015 |
| Surefood Ltd | Hospitality | 2017 |
| Suresense Technologies Limited | Manufacturing | 2012 |
| Surface Studios Ltd | Wholesale & retail | 2025 |
| Survive & Revive Limited | Education | 2024 |
| Sustainability Cornwall Ltd | Professional & scientific | 2024 |
| Sustainable Composites Limited | Professional & scientific | 2002 |
| SW Formwork Ltd | Construction | 2026 |
| Sweet House 888 Ltd | Hospitality | 2023 |
| Sweet Soul Company Ltd | Wholesale & retail | 2026 |
| Swim Academy for Babies Ltd | Education | 2008 |
| Swrpc Limited | Wholesale & retail | 2015 |
| Szelesi Property Holdings Ltd | Construction | 2026 |