| Hawksridge Ltd | Agriculture & fishing | 2025 |
| HCF Consultancy Services Ltd | Professional & scientific | 2019 |
| Heat Store Services (Cornwall) Limited | Construction | 2011 |
| Helm Hospitality Ltd | Information & communication | 2026 |
| Henderson L Limited | Wholesale & retail | 2018 |
| Henry J.Clare Limited | Construction | 1935 |
| Heritage Land & Estates Limited | Construction | 1994 |
| HF Cantina Ltd | Hospitality | 2025 |
| Hhwc Ltd | Extraterritorial | 2024 |
| High Hedley Limited | Energy | 2026 |
| Higher Goonamarth Turbine Ltd | Energy | 2014 |
| Higher Treveglos Limited | Hospitality | 1961 |
| Highstead Homes Limited | Construction | 2003 |
| Holiday Home Garden Maintenance Ltd | Administrative & support | 2019 |
| Holiday Home Waste Collection Ltd | Water & waste | 2018 |
| Holmbush Cottage Management Limited | Hospitality | 2008 |
| Honicombe Ltd | Arts & recreation | 2009 |
| Hot Tigs Limited | Manufacturing | 2025 |
| House Supply Co Ltd | Wholesale & retail | 2020 |
| HQ Tavistock Limited | Hospitality | 2013 |
| I Marshall & Sons LLP | | 2009 |
| ICT Connect Limited | Information & communication | 1998 |
| Idcta Limited | Professional & scientific | 2014 |
| Imperium Cornwall Limited | Construction | 2025 |
| Impress 51 Limited | Professional & scientific | 2017 |
| Independent Local Newspapers Limited | Information & communication | 1998 |
| Inferno Developments Limited | Construction | 2025 |
| Inferno Groundworks Limited | Construction | 2025 |
| Inox Stainless & Aluminium Ltd | Manufacturing | 2023 |
| Intensive Power Ltd | Administrative & support | 2023 |
| Irons Brothers Holdings Limited | Real estate | 2021 |
| Istcc (UK) Ltd | Arts & recreation | 2013 |
| J B Crooks Ltd | Professional & scientific | 2022 |
| Jackson Gallery Ltd | Arts & recreation | 2019 |
| Jacobs Property Management Ltd | Real estate | 2019 |
| Jago Holdings Ltd | Construction | 2022 |
| Jaimie-Beth & Co Ltd | Professional & scientific | 2025 |
| JBY1 Consulting Limited | Extraterritorial | 2023 |
| JJ Bathrooms Ltd | Wholesale & retail | 2023 |
| JLM Plastering Limited | Construction | 2013 |
| Jmet Holdings Ltd | Real estate | 2023 |
| JO & Co Home Limited | Wholesale & retail | 2014 |
| JOE Edkins Plumbing & Heating Limited | Construction | 2026 |
| JOE Reuben Carter Limited | Information & communication | 2003 |
| Joegelly Limited | Construction | 2015 |
| John Bray & Partners Estate Agents LLP | | 2019 |
| John MH Bellhouse Ltd | Professional & scientific | 2019 |
| Joulberry Limited | Manufacturing | 2010 |
| JPM Cornwall Developments Ltd | Construction | 2026 |
| K R Property and Developments Ltd | Real estate | 2025 |
| K.S.W. Projects Ltd | Construction | 2020 |
| Kalitico Limited | Extraterritorial | 2023 |
| Kara Cornwall Limited | Education | 2012 |
| Karvenow Limited | Construction | 2020 |
| Kate Bickford Unique Cornwall Homes Ltd | Real estate | 2024 |
| KC Mundy Consulting Limited | Information & communication | 2022 |
| KDJ QS Services Limited | Professional & scientific | 2017 |
| Kelsea Limited | Other services | 2019 |
| Kennet OIL Logistics Limited | Mining & quarrying | 2007 |
| Kernel Data Ltd | Information & communication | 2014 |
| Kernow Coal & Fires Limited | Wholesale & retail | 2005 |
| Kernow Confectionery Ltd | Manufacturing | 1978 |
| Kernow Fireworks Ltd | Other services | 2020 |
| Kernow Pubs Ltd | Hospitality | 2020 |
| Kersworthy Mortgage Services Limited | Financial services | 2025 |
| Kerthnow Properties Ltd | Real estate | 2024 |
| Keybuild (SW) Ltd | Construction | 2018 |
| Keystone Consultants (UK) Limited | Professional & scientific | 2011 |
| Khantara Ltd | Wholesale & retail | 2025 |
| Kirsi Ltd | Information & communication | 2026 |
| Knight Engine Testing Limited | Manufacturing | 2005 |
| Knight Racing Services Limited | Manufacturing | 1996 |
| Koura Limited | Professional & scientific | 2016 |
| L&R Luxury Travel Ltd. | Administrative & support | 2015 |
| L'Luxe Aesthetics Ltd | Other services | 2025 |
| LA Farmhouse Limited | Real estate | 2025 |
| LA. Co Consultancy Limited | Information & communication | 2026 |
| Lane's Auto Repairs Ltd. | Wholesale & retail | 2021 |
| Leadbetter Holdings Limited | Financial services | 2021 |
| LEE Doney Building and Carpentry Limited | Construction | 2014 |
| Legrys Lettings Limited | Real estate | 2017 |
| Leisure & Commercial Limited | Professional & scientific | 1995 |
| Lemon Arms Mylor Ltd | Hospitality | 2025 |
| Lemonwalk Limited | Real estate | 1987 |
| Lend & Borrow Trust Company Limited | Information & communication | 2014 |
| Linear Investment Consultants Limited | Information & communication | 2015 |
| Little Cocoa Ltd | Wholesale & retail | 2023 |
| Little Dinham Limited | Hospitality | 2011 |
| Little Egret Property Limited | Real estate | 2021 |
| Little Jobs Cornwall Ltd | Construction | 2024 |
| Little Orchard Properties 2 Limited | Real estate | 2016 |
| Little Orchard Properties Holdings Limited | Real estate | 2016 |
| Little Orchard Properties Limited | Real estate | 2013 |
| Llawnroc Ceilings and Partitions Limited | Construction | 2003 |
| LLW Surf Limited | Wholesale & retail | 2021 |
| Lodge Farm Turbine Ltd | Energy | 2016 |
| London Diving Centre Ltd | Education | 2021 |
| Long Dog Accounts Limited | Professional & scientific | 2025 |
| Long Wave Limited | Real estate | 2025 |
| Lore & Alchemy Limited | Wholesale & retail | 2023 |