| Harvest Renewables Cornwall Limited | Construction | 2012 |
| Harwoods Southwest Limited | Hospitality | 2014 |
| Hatfield Crescent Management Company Limited | Households | 2002 |
| Haven Construction Ltd | Construction | 2017 |
| Hawkins Social Work Consultancy Limited | Health & social care | 2026 |
| Headland Holdings Limited | Financial services | 2021 |
| Healing to Zero Limited | Health & social care | 2026 |
| Helios Cornwall Limited | Extraterritorial | 2015 |
| Helvank Ltd | Real estate | 2025 |
| Hemsley Hydro Ltd | Agriculture & fishing | 2018 |
| Hendra Limited | Administrative & support | 2000 |
| Hendra Manor (NO. 2) Limited | Construction | 2009 |
| Hendra Touring Caravan & Camping Park Limited | Hospitality | 1972 |
| Henver Court Management Company Limited | Households | 1988 |
| Henwood Court Management Company Limited | Households | 1988 |
| Henwood Engineering Ltd | Professional & scientific | 2017 |
| Henwood Funerals Limited | Other services | 2023 |
| Heron Sports Management Company Limited | Arts & recreation | 2001 |
| Heybrook Mews Ltd | Households | 2022 |
| Higgins Newquay Ltd | Hospitality | 2019 |
| High and DRY Ltd | Professional & scientific | 2024 |
| Higher Tower Road Management Company Limited | Real estate | 2006 |
| Highfields Management Company (Cubert) Limited | Households | 2023 |
| Highways Plant Limited | Administrative & support | 2006 |
| Higman Windows Limited | Construction | 2004 |
| HJM Tree Services Limited | Agriculture & fishing | 2024 |
| Hobbybox.Club Limited | Wholesale & retail | 2020 |
| Holywell Beach Bar Limited | Hospitality | 2023 |
| Holywell Car Park Limited | Administrative & support | 2023 |
| Holywell Hire Ltd | Administrative & support | 2023 |
| Home & Industrial Building Services (Hull) Limited | Construction | 2002 |
| Home Counties Nurseries and Day Care Ltd | Education | 2019 |
| Home Nansledan Ltd | Wholesale & retail | 2019 |
| Homeroot Ltd | Construction | 2011 |
| Homested Developments Limited | Construction | 2022 |
| Hoof Solutions Limited | Wholesale & retail | 2026 |
| Hooper Surveying Ltd | Construction | 2011 |
| Hope Yard Trading Limited | Real estate | 2026 |
| Horizons RTM Company Limited | Households | 2016 |
| Horkesley Joinery Limited | Construction | 2015 |
| Hot Box (Southwest) Ltd | Hospitality | 2025 |
| Hotdraw UK Ltd | Arts & recreation | 2020 |
| House of Clean Energy Ltd | Extraterritorial | 2024 |
| House of Glass Corporation Limited | Manufacturing | 2025 |
| House of Leela Ltd | Wholesale & retail | 2024 |
| House of Margaux Limited | Manufacturing | 2018 |
| HP Training & Consultancy Limited | Professional & scientific | 2006 |
| Human Capability Partners Ltd | Professional & scientific | 2023 |
| HUS Homes Ltd | Real estate | 2025 |
| Hutton Hire Limited | Administrative & support | 2013 |
| Hybrid Hub SW Ltd | Other services | 2025 |
| Hybrock Ltd | Transport & logistics | 2021 |
| Hybryd Limited | Wholesale & retail | 2020 |
| Hyperionwave Limited | Information & communication | 2025 |
| I C Building Consultancy Limited | Professional & scientific | 2023 |
| I SPY Solar Ltd | Construction | 2022 |
| IAN Harrison Photography Limited | Professional & scientific | 2013 |
| IAN White Design Ltd | Professional & scientific | 2026 |
| Ice Cold Studios Ltd | Administrative & support | 2017 |
| Ideal Bikes and Boards Ltd | Wholesale & retail | 2010 |
| Igem Limited | Extraterritorial | 2008 |
| IGN Group Holdings Ltd | Financial services | 2019 |
| IGN Holdings Ltd | Hospitality | 2018 |
| Ikonek Holdings Limited | Financial services | 2025 |
| Imove Newquay Ltd | Real estate | 2015 |
| Imove Property Investments Limited | Real estate | 2020 |
| Inbound Scaling Ltd | Information & communication | 2022 |
| Incamar Ltd | Hospitality | 2020 |
| Inclusive Music Ltd | Education | 2014 |
| Incy Properties Ltd | Real estate | 2024 |
| Independent Living (Newquay) Limited | Wholesale & retail | 2015 |
| Independent Park Home Advisory Service (2021) Ltd | Other services | 2021 |
| Infinite Missions Wellbeing CIC | Education | 2026 |
| Inmalets Ltd | Real estate | 2025 |
| Inner Tide Limited | Wholesale & retail | 2023 |
| Insight Recovery Network Ltd | Health & social care | 2025 |
| Integer Solutions Limited | Manufacturing | 2004 |
| International Diversity Food Festival for Cornwall CIC | Hospitality | 2024 |
| International Fugitive Emissions Abatement Association Limited | Information & communication | 2020 |
| Ionxo Ltd | Manufacturing | 2025 |
| IRM Geosciences Ltd | Professional & scientific | 2019 |
| Isho Creative Limited | Professional & scientific | 2018 |
| Island Reach Residents Association Limited | Real estate | 2016 |
| Issey Active Ltd | Wholesale & retail | 2022 |
| ISTANBUL2334 Limited | Hospitality | 2018 |
| It's Always Overhead Limited | Wholesale & retail | 2021 |
| ITP Electrical Limited | Mining & quarrying | 2010 |
| J & J Cornwall Limited | Wholesale & retail | 2022 |
| J Hocking Consultancy Ltd | Administrative & support | 2012 |
| J JAY Tiling Limited | Construction | 2015 |
| J L Riley Ltd | Professional & scientific | 2007 |
| J Stone SS Ltd | Professional & scientific | 2019 |
| J. Mortimer Ltd | Manufacturing | 2022 |
| J. Todman Plant Hire Ltd | Administrative & support | 2015 |
| J.E. Produce Ltd | Wholesale & retail | 2014 |
| Jack Benney Limited | Construction | 2002 |
| Jack's Deliveries Ltd | Transport & logistics | 2025 |
| Jacksons Wine Bar Nansledan Ltd | Hospitality | 2024 |
| Jacqui's House Limited | Construction | 2023 |
| Jaflong Catering Limited | Hospitality | 2015 |