| JE Build Limited | Construction | 2023 |
| Jelly Pixel Design Ltd | Arts & recreation | 2017 |
| JEM Instrumentation and Controls Ltd | Professional & scientific | 2008 |
| Jempower Limited | Energy | 2015 |
| JET Power Pressure Washing Ltd | Administrative & support | 2024 |
| JFM Property Solutions Limited | Construction | 2024 |
| JHA (Cornwall) Limited | Construction | 2010 |
| Jhamecz Ltd | Education | 2026 |
| JJ Mobile Mechanics Ltd | Wholesale & retail | 2025 |
| JM Groundworks & Landscaping Ltd | Construction | 2024 |
| JMC Conversions Limited | Construction | 2001 |
| Joseph's Turquoise Ltd | Hospitality | 2026 |
| Joy Plant Ltd | Administrative & support | 2016 |
| JPS - Sales (SW) Ltd | Wholesale & retail | 2017 |
| Jumbocolor Ltd. | Manufacturing | 2000 |
| Jumping Bean Burrito Company Limited | Hospitality | 2011 |
| Justin Eyre Plumbing & Heating Ltd | Construction | 2011 |
| Justin Roberton Limited | Wholesale & retail | 2008 |
| JW Leisure Cornwall Ltd | Arts & recreation | 2021 |
| Jynn Ltd | Information & communication | 2026 |
| K a Groundworks Southwest Limited | Construction | 2013 |
| K B Construction South West Ltd | Construction | 2023 |
| K D Chapman & Company Limited | Professional & scientific | 2008 |
| K Hill & Partners Ltd | Administrative & support | 2011 |
| K Meadow (Launceston) Management Company Limited | Households | 2024 |
| K P Properties (Cornwall) Limited | Construction | 1995 |
| K. Lias Building Ltd | Construction | 2026 |
| Kalashnisoft Ltd | Arts & recreation | 2025 |
| Kamaachi UK Ltd | Wholesale & retail | 2026 |
| Kaori Limited | Information & communication | 2008 |
| Karma Xpress Ltd | Hospitality | 2025 |
| Kastel Stret Garage Limited | Real estate | 2024 |
| Kate Rogers Creative Academy CIC | Education | 2023 |
| Katie Skea Limited | Professional & scientific | 2024 |
| Kay's Mews Management Company Limited | Extraterritorial | 2003 |
| KBM Construction S W Ltd | Construction | 2023 |
| Kbsk Performing Arts CIC | Arts & recreation | 2018 |
| KDS Service Centre Limited | Wholesale & retail | 2024 |
| Kearnsweir Limited | Hospitality | 2015 |
| Keaters Farm Shop Ltd | Wholesale & retail | 2024 |
| Kellan Productions Ltd | Information & communication | 2020 |
| Kelly Green Limited | Energy | 2012 |
| Kelly's of Bodmin Limited | Wholesale & retail | 2002 |
| Kelly's SW Limited | Financial services | 2025 |
| Kelsey House Apartments Management Company Limited | Households | 2024 |
| Kennel Consultancy Ltd | Professional & scientific | 2017 |
| Kernewek Trevow Limited | Real estate | 2019 |
| Kernick Holdings Limited | Real estate | 2018 |
| Kernow Atelier Ltd | Professional & scientific | 2026 |
| Kernow Cooling Ltd | Construction | 2019 |
| Kernow Flying Club Ltd | Other services | 2026 |
| Kernow Hospitality Group Ltd | Hospitality | 2021 |
| Kernow Management Systems Limited | Professional & scientific | 2024 |
| Kernow RV Limited | Arts & recreation | 2020 |
| Kernow Slide Ltd | Hospitality | 2023 |
| Kernow Smart Accounting Ltd | Professional & scientific | 2014 |
| Kernow Springs Limited | Wholesale & retail | 2025 |
| Kernow Technology Ltd | Information & communication | 2026 |
| Kernow Wind Limited | Construction | 2026 |
| Kersworthy Asset Management Limited | Agriculture & fishing | 2024 |
| Kertouche Limited | Hospitality | 2025 |
| Kestrel Electronic Components Limited | Other services | 1983 |
| Kingswood Energy Ltd | Energy | 2013 |
| Kingswood Shoot Limited | Agriculture & fishing | 2011 |
| King’S Deliveries Ltd | Transport & logistics | 2020 |
| KJT Trading Ltd | Hospitality | 2019 |
| KMD Developments Limited | Construction | 2009 |
| KNJ Stonemasons Ltd | Construction | 2022 |
| Kolar Management Company Limited | Households | 2012 |
| Koti Property Management Limited | Real estate | 2019 |
| Kowel Gwenen: the Hive C.I.C. | Education | 2024 |
| Kriger Apparel Ltd | Wholesale & retail | 2020 |
| Kubertron Limited | Information & communication | 2016 |
| Kyldenna Limited | Administrative & support | 2013 |
| L & B Sharpe Properties Ltd | Hospitality | 2023 |
| L & P Difford LLP | | 2013 |
| L Schofield Plumbing and Heating Ltd | Construction | 2026 |
| Labyrinth Gallery Ltd | Professional & scientific | 2020 |
| Lakeshore Data Management Ltd. | Information & communication | 2016 |
| Lakeview Court RTM Company Limited | Households | 2017 |
| Lala Barber Bodmin Ltd | Other services | 2022 |
| Langcombe Properties Ltd | Construction | 2020 |
| Langlebuild (South West) Limited | Construction | 2011 |
| Lanhydrock Estate Company(The) | Real estate | 1934 |
| Lanhydrock Garden Services Ltd | Administrative & support | 2007 |
| Lanhydrock Golf Club Limited | Hospitality | 1996 |
| Lanivet Hub Community Interest Company | Hospitality | 2026 |
| Lanlivery Farm Limited | Agriculture & fishing | 2010 |
| LEE West & Co Limited | Agriculture & fishing | 2022 |
| Legacy AV Limited | Professional & scientific | 2021 |
| LEK Electrical Limited | Extraterritorial | 2010 |
| Lending Hands in Care Ltd | Health & social care | 2023 |
| Levtext Limited | Professional & scientific | 2024 |
| LG Light Haulage Ltd | Transport & logistics | 2024 |
| Light and Vision Recruitment Ltd | Administrative & support | 2025 |
| Light the Flame CIC | Arts & recreation | 2022 |
| Lipsmackers LLP | | 2024 |
| Little & Large Events Ltd | Administrative & support | 2024 |
| Lloyd Electrical Limited | Construction | 2024 |
| Lmabb Limited | Other services | 2020 |