| Hewden Construction Limited | Construction | 2023 |
| HGL Consultancy Limited | Professional & scientific | 2020 |
| HGL Properties Limited | Real estate | 2020 |
| High Definition Surveys Ltd | Administrative & support | 2009 |
| High Gables (Ranskill) Management Company Limited | Households | 2017 |
| Higher Tier Systems Limited | Information & communication | 2015 |
| Highfield Farms (Stokeham) Limited | Agriculture & fishing | 1965 |
| Hill Properties South Yorkshire Ltd | Households | 2025 |
| Hillman Holdings Ltd | Financial services | 2024 |
| HMW Healthcare Ltd | Wholesale & retail | 2022 |
| Hola Sherry Ltd | Wholesale & retail | 2026 |
| Holdings by RJ Ltd | Real estate | 2025 |
| Holistique Aesthetics Ltd | Other services | 2025 |
| Holistium Technologies Limited | Professional & scientific | 2020 |
| Holly Mount Ltd | Construction | 2022 |
| Holly Mount Management Company (Retford) Limited | Households | 2004 |
| Holmes for Hope CIC | Hospitality | 2026 |
| Holmes Ground Care Maintenance Ltd | Administrative & support | 2019 |
| HOLMES4HOMES Property Ltd | Real estate | 2024 |
| Holyspirit Property Limited | Real estate | 2024 |
| Home Farm Produce Grove Limited | Agriculture & fishing | 2022 |
| Homekare Agency Services Limited | Health & social care | 2026 |
| Homekare Community Services Limited | Health & social care | 2026 |
| Homespace Creations Ltd | Construction | 2020 |
| Honour Scaffolding and Construction Ltd | Construction | 2021 |
| Horse Drawn Dining Carriages Limited | Hospitality | 2020 |
| Horsepower Therapies Limited | Health & social care | 2019 |
| Hospital of the Holy and Undivided Trinity Trustee Limited | Administrative & support | 2025 |
| House of Holistics and Beauty Ltd | Other services | 2026 |
| Howard & Co Farming Limited | Agriculture & fishing | 2014 |
| Howard (Retford) Limited | Real estate | 2014 |
| Howard Equestrian Limited | Agriculture & fishing | 2011 |
| Howard Renewables Limited | Real estate | 2022 |
| Howpow Limited | Manufacturing | 2013 |
| HR Fire & Security Ltd | Public administration | 2015 |
| HR Property Developments Ltd | Real estate | 2020 |
| HTX Products Ltd | Mining & quarrying | 2022 |
| Hughes Construction & Consultancy Ltd | Construction | 2025 |
| Hugsly Fugsly Ltd | Administrative & support | 2021 |
| Humanideia UK Ltd | Education | 2026 |
| Hunter Scott Ltd | Professional & scientific | 2019 |
| Hunts Agricultural Services Ltd | Agriculture & fishing | 2017 |
| Hunts Contractors Limited | Construction | 2005 |
| Hunts Plant Ltd | Construction | 2021 |
| Hunts SPV One Ltd | Real estate | 2006 |
| Huntsman’S Game Limited | Manufacturing | 2021 |
| Hutchinson Asset Management Limited | Administrative & support | 2017 |
| Hybrid Products Ltd | Wholesale & retail | 2023 |
| Hybrid Retford Ltd | Administrative & support | 2025 |
| Hype Web Design Ltd | Professional & scientific | 2020 |
| I Floor Europe Ltd | Construction | 2025 |
| I.D. Spares & Service Limited | Manufacturing | 1997 |
| IAN & Jenny Stephens Ltd | Administrative & support | 2009 |
| IAN Smith Installations Limited | Construction | 2026 |
| Icarus Promotions Limited | Administrative & support | 2018 |
| Icon Aerospace Technology Ltd | Manufacturing | 1933 |
| ICS Renewables Limited | Real estate | 2017 |
| ICS Scaffolding Services Limited | Construction | 2025 |
| ID3 Asset Management Limited | Water & waste | 2008 |
| Idle River Limited | Wholesale & retail | 2020 |
| Idle Valley Limited | Extraterritorial | 2014 |
| Idle Valley TAP Limited | Hospitality | 2018 |
| Igsense Limited | Professional & scientific | 2013 |
| IJA Consultancy Limited | Professional & scientific | 2025 |
| IMA Dairy & Food UK Limited | Professional & scientific | 2019 |
| Images Galleries Limited | Wholesale & retail | 1998 |
| Impactive Care Ltd | Other services | 2017 |
| Imperial Gourmet Limited | Hospitality | 2026 |
| Impulse Amaze Ltd | Other services | 2023 |
| IN the Detail (Notts) Ltd | Administrative & support | 2011 |
| IN the Spotlight Ltd | Extraterritorial | 2020 |
| Independent Wealth Management Consultants Ltd | Financial services | 1973 |
| Index Property Investment Ltd | Real estate | 2026 |
| Indigoblu Limited | Manufacturing | 2010 |
| Infinite Sales Solutions Limited | Administrative & support | 2018 |
| Infinity.I.T Ltd | Information & communication | 2020 |
| Informd Consulting Ltd | Professional & scientific | 2024 |
| Inkpot Monkey Limited | Extraterritorial | 2010 |
| Innegroup Limited | Hospitality | 2021 |
| Inspired Hospitality Limited | Hospitality | 2022 |
| INT Fabrications Co Ltd | Manufacturing | 2022 |
| INT Profile and Fold Ltd | Manufacturing | 2025 |
| INT Specialist Haulage Ltd | Transport & logistics | 2024 |
| Intelligent Drainage Solutions Group Ltd | Financial services | 2025 |
| Intelligent Drainage Solutions Limited | Water & waste | 2013 |
| Intelligent Illumination Ltd | Professional & scientific | 2017 |
| Inter Real Estate Ltd | Hospitality | 2021 |
| Inter-Lec Limited | Manufacturing | 1993 |
| International Beauty Training Ltd | Public administration | 2021 |
| Internet Insurance (Holdings) Limited | Financial services | 2013 |
| Internet Insurance Services UK Ltd | Financial services | 2000 |
| Intruda Limited | Administrative & support | 2017 |
| Iris Surgical Limited | Health & social care | 2012 |
| Irontree Designs Limited | Wholesale & retail | 2014 |
| It's NOT Smoke Ltd | Wholesale & retail | 2019 |
| J & J Stores Ltd | Wholesale & retail | 2013 |
| J and E Property Holdings Limited | Real estate | 2021 |
| J Foster Properties Limited | Real estate | 2012 |
| J Gale Farming Limited | Agriculture & fishing | 2019 |
| J M Tomlinson Limited | Real estate | 2018 |