| Inspired Solutions (SW) Limited | Professional & scientific | 2025 |
| Insula Developments Ltd | Construction | 2026 |
| Intercerve Limited | Construction | 2014 |
| Intotri Events Ltd | Arts & recreation | 2025 |
| Invest Hub Property Ltd | Real estate | 2025 |
| Ireson Roberts Properties Ltd | Real estate | 2020 |
| Issie Limited | Wholesale & retail | 2025 |
| Izzy Pullen Media Ltd | Information & communication | 2021 |
| J & B Design Limited | Construction | 2010 |
| J Bentley Developments Limited | Construction | 2025 |
| J C Orchard Masonry and Groundworks Limited | Construction | 2022 |
| J Gardiner Limited | Professional & scientific | 2014 |
| J R Flat Roofing U K Limited | Construction | 1993 |
| Jackson Developments (Cornwall) Limited | Construction | 2022 |
| Jackson Fine Homes Limited | Construction | 1987 |
| Jade Supplies Ltd | Health & social care | 2025 |
| James Contracting Ltd | Construction | 2018 |
| James MB Limited | Professional & scientific | 2024 |
| Jardine Karate Ltd | Arts & recreation | 2009 |
| Jasmine Cole Productions and Management Ltd | Arts & recreation | 2025 |
| Java Ltd | Hospitality | 2024 |
| JBA Souvenirs Limited | Wholesale & retail | 2024 |
| JBV Builders Ltd | Construction | 2016 |
| JDS Properties and Developments Limited | Construction | 2007 |
| JEB Supplies Limited | Wholesale & retail | 2003 |
| Jenni Dandy Ltd | Education | 2022 |
| Jennings & Co (Cwll) Limited | Professional & scientific | 2026 |
| JF2 Ltd | Construction | 2026 |
| JI Beauty Academy Ltd | Other services | 2022 |
| Jillyrox Limited | Manufacturing | 2015 |
| Jim's Redruth Taxis Ltd | Transport & logistics | 2025 |
| Jims (South West) Ltd | Wholesale & retail | 2024 |
| Jims BD Ltd | Wholesale & retail | 2024 |
| Jims CB Ltd | Extraterritorial | 2024 |
| Jims PZ Ltd | Wholesale & retail | 2024 |
| JJ Construction (SW) Ltd | Construction | 2017 |
| JJ KOI Limited | Hospitality | 2023 |
| JL Construction Cornwall Ltd | Construction | 2021 |
| Jobz a Keepa Ltd | Administrative & support | 2023 |
| John Boyle Solicitors Limited | Professional & scientific | 2014 |
| John's Service Centre Limited | Wholesale & retail | 2004 |
| Josephs Court Limited | Households | 1974 |
| JP Electrical South West Ltd | Construction | 2012 |
| JRG Engineering Cornwall Ltd | Manufacturing | 2021 |
| JRO Bar & Events Ltd | Hospitality | 2023 |
| JS Construction Solutions Limited | Construction | 2020 |
| JSJ Design Limited | Agriculture & fishing | 2014 |
| JSL88 Limited | Real estate | 2014 |
| JSR Holdings Cornwall Ltd | Financial services | 2023 |
| JSR Showrooms Ltd | Construction | 2013 |
| Jtps Properties Limited | Real estate | 2012 |
| Ju-Ark Properties Ltd | Real estate | 2025 |
| JXW Enterprises Holdings Limited | Financial services | 2024 |
| JXW Enterprises Limited | Real estate | 2024 |
| K & G Developments ST Ives Limited | Construction | 2021 |
| K & R Blewett Limited | Construction | 2002 |
| K & R Couriers Limited | Transport & logistics | 2010 |
| K Viles Consultancy Limited | Professional & scientific | 2020 |
| K W Autos Cornwall Ltd | Wholesale & retail | 2011 |
| Kaarmauk Ltd | Hospitality | 2020 |
| Kabuki Hair and Beauty Limited | Other services | 2012 |
| Kamran Cabs Ltd | Transport & logistics | 2026 |
| KAT Speed Ltd | Transport & logistics | 2021 |
| Katie's Cornish Hotpots Limited | Hospitality | 2016 |
| Kaur Carpets and Flooring Ltd | Construction | 2025 |
| Kaur Carpets Ltd | Construction | 2016 |
| KC Solar Limited | Construction | 2025 |
| KC Space Limited | Professional & scientific | 2023 |
| Keane Lettings Ltd | Real estate | 2026 |
| Keith Rogers Limited | Administrative & support | 2025 |
| Kelast Ltd | Financial services | 2026 |
| Keltek Cornish Brewery Limited | Manufacturing | 1997 |
| Kelwyn Court Residents Association Limited | Households | 1988 |
| Kemp Engineering and Surveying Ltd. | Professional & scientific | 1996 |
| Kennedy Nash Limited | Financial services | 2024 |
| Kenyon Agencies Ltd | Manufacturing | 2004 |
| Kernewek INK Ltd | Arts & recreation | 2025 |
| Kernow 247 Ltd | Construction | 2024 |
| Kernow BJJ Limited | Administrative & support | 2018 |
| Kernow Business Agency Limited | Administrative & support | 2023 |
| Kernow Business Messaging Service LLP | | 2009 |
| Kernow Cat Hotel Ltd | Hospitality | 2019 |
| Kernow Catering Equipment South West Limited | Wholesale & retail | 2020 |
| Kernow Clinical Waste Limited | Water & waste | 2016 |
| Kernow Education Arts Partnership | Education | 2001 |
| Kernow Furniture Ltd | Wholesale & retail | 2013 |
| Kernow H2O Ltd | Wholesale & retail | 2026 |
| Kernow Kitchens Ltd | | 2007 |
| Kernow Message Handling Service Limited | Information & communication | 1996 |
| Kernow Mining Optimisation - Fleet Ltd | Mining & quarrying | 2022 |
| Kernow Music Foundation Community Interest Company | Information & communication | 2014 |
| Kernow Property Limited | Real estate | 2025 |
| Kernow Regalia Ltd | Wholesale & retail | 2025 |
| Kernow Takeaway Ltd | Hospitality | 2024 |
| Kernow Truck & Van Ltd | Wholesale & retail | 2021 |
| Kernow Vending Ltd | Hospitality | 2015 |
| Kernow Venues Ltd | Hospitality | 2024 |
| Kernow Windows Ltd | Construction | 2018 |
| Kernowlaw Ltd | Professional & scientific | 2016 |
| Kerrier Cabs Limited | Transport & logistics | 2024 |