| Class Management Limited | Households | 1986 |
| Classic Cornish Hampers Ltd | Hospitality | 2019 |
| Claymore Construction Services Limited | Construction | 2005 |
| Cloverleif Limited | Manufacturing | 2022 |
| Cloverpark Leasing Limited | Administrative & support | 2000 |
| Coaching With FAY Ltd | Professional & scientific | 2025 |
| Coast to Country Town Planning Ltd | Professional & scientific | 2025 |
| Cochise Carpentry Ltd | Manufacturing | 2026 |
| Codewind Limited | Construction | 2016 |
| Coldrenick Farms Limited | Agriculture & fishing | 1959 |
| Commando Health and Fitness Limited | Arts & recreation | 2016 |
| Commonmoor Community Funding Limited | Arts & recreation | 2016 |
| Community Sleep Service CIC | Health & social care | 2024 |
| Community Treasure Chest CIC | Wholesale & retail | 2016 |
| Compass Consulting Engineers Ltd | Professional & scientific | 2022 |
| Complete Competence Limited | Information & communication | 2021 |
| Complex Rehab Group Holdings Limited | Financial services | 2024 |
| Consultittech Ltd | Information & communication | 2015 |
| Continuum (Marketing) Ltd | Financial services | 2013 |
| Continuum Financial Ltd | Financial services | 2015 |
| Coombe Farm Holidays Limited | Hospitality | 2018 |
| Cooper Enterprises of UK Ltd | Wholesale & retail | 2017 |
| Cooplet Ltd. | Hospitality | 2017 |
| Copperleaf Polperro Limited | Hospitality | 2024 |
| Copplestone Cars Limited | Wholesale & retail | 2016 |
| Cornish Bluebelle Ltd | Wholesale & retail | 2020 |
| Cornish Engineering Surveys Ltd | Professional & scientific | 2005 |
| Cornish Tea & Cornish Coffee Co Ltd | Wholesale & retail | 2012 |
| Cornish Tea & Cornish Coffee Holdings Limited | Financial services | 2017 |
| Cornish Tea Trading Ltd | Wholesale & retail | 2013 |
| Cornish Trees and Gardens Ltd | Agriculture & fishing | 2020 |
| Cornwall Campervan Conversions Limited | Manufacturing | 2022 |
| Cornwall Cars Ltd | Wholesale & retail | 2024 |
| Cornwall Cctv Ltd | Administrative & support | 2019 |
| Cornwall Electrical Services Limited | Construction | 2025 |
| Cornwall Groundworks Ltd | Construction | 2015 |
| Cornwall Home Renovations Ltd | Construction | 2025 |
| Cornwall Musical Theatre & Performing Arts | Arts & recreation | 2026 |
| Cornwall Typing Services Limited | Administrative & support | 2014 |
| Cotton Bays Cleaning Services Ltd | Administrative & support | 2023 |
| Cotton Bays Laundry Company Ltd | Other services | 2021 |
| Country Lane Enterprises Limited | Hospitality | 2014 |
| Country Lane Foods Limited | Wholesale & retail | 2003 |
| County Tea & Coffee Ltd | Wholesale & retail | 2023 |
| Cranborne Carpentry Limited | Construction | 2006 |
| Ctrl+Alt+Create Limited | Health & social care | 2025 |
| Cudark Limited | Extraterritorial | 2023 |
| Curtis Scaffolding Limited | Construction | 2010 |
| D J Ball Solutions Limited | Construction | 2021 |
| D J F Greaves Ltd | Administrative & support | 2003 |
| D&J Window Cleaners Ltd | Other services | 2025 |
| DAM Civil Engineering Limited | Construction | 2003 |
| Dance Centred C.I.C. | Health & social care | 2019 |
| Danst Properties Limited | Real estate | 2017 |
| Darley Ford Limited | Transport & logistics | 2014 |
| Darrion JAY Group Limited | Transport & logistics | 2016 |
| David Lucas Training Ltd | Education | 2022 |
| DCS Pest Control (Cornwall) Limited | Administrative & support | 2015 |
| DD Electronics Ltd | Manufacturing | 2015 |
| Denwood House Management Company Limited | Households | 2020 |
| Derwen Group Ltd | Agriculture & fishing | 2026 |
| Desico Ltd | Information & communication | 2021 |
| Detailer Directory Ltd | Information & communication | 2023 |
| Devon & Cornwall Boiler & Heating Spares Limited | Extraterritorial | 2005 |
| Devon Tea & Devon Coffee Co Ltd | Manufacturing | 2022 |
| Diamond Biodiversity Holdings Ltd | Financial services | 2020 |
| Digital Finesse Limited | Wholesale & retail | 2026 |
| Digital South West Ltd | Information & communication | 2024 |
| Dinas Court Members Ltd | Households | 1992 |
| Discovery House Management Company Limited | Households | 2018 |
| Dive Control Systems Ltd | Professional & scientific | 2024 |
| DJ Templating Ltd | Professional & scientific | 2025 |
| DJM Cornwall Limited | Other services | 2006 |
| DJP Groundwork & Building Ltd | Construction | 2011 |
| DJW Build Ltd | Construction | 2006 |
| Domtex Wholesale Ltd | Manufacturing | 2025 |
| Dotcom Hustle Ltd | Wholesale & retail | 2018 |
| Dotzle Ltd | Information & communication | 2025 |
| Doublebois House Management Company Limited | Hospitality | 1990 |
| Doublebois MOT Testing Limited | Wholesale & retail | 2024 |
| Dovetail Ministries Ltd | Information & communication | 2007 |
| Doyle & Whitley Ltd | Construction | 2011 |
| Drawbridge Inn Limited | Hospitality | 2017 |
| Dsouzapr Ltd | Professional & scientific | 2013 |
| Duchy Loft Conversions Ltd | Construction | 2018 |
| Duloe Community Shop CIC | Wholesale & retail | 2011 |
| DV Asset Management Limited | Financial services | 2019 |
| DVS Groundwork’S Ltd | Construction | 2026 |
| E Bikes Cornwall Ltd | Administrative & support | 2019 |
| Earl and Crocker Limited | Professional & scientific | 2012 |
| Earle Management Limited | Professional & scientific | 2025 |
| Earth and Stone Limited | Hospitality | 2015 |
| Ecat Networks Limited | Information & communication | 2006 |
| Eccabi Ltd | Administrative & support | 1998 |
| Eco-Bos Construction Ltd | Construction | 2019 |
| Eco-Bos Development Limited | Construction | 2008 |
| Ecological Surveys Limited | Professional & scientific | 2012 |
| Ecology Matters Ltd | Extraterritorial | 2020 |
| EDB Cornwall Properties Ltd | Real estate | 2026 |
| Edgecomb House Management Company Ltd | Households | 2015 |