| Hinkson Homes Limited | Construction | 2023 |
| Hinkson Interiors Limited | Construction | 2015 |
| Hioxpa Ltd | Professional & scientific | 2025 |
| Hipparchus Graphics Ltd | Information & communication | 2013 |
| Historic Motorsport Fabrication Ltd | Wholesale & retail | 2016 |
| Hitcham Enterprises Limited | Hospitality | 2018 |
| Hmoproject Ltd | Real estate | 2021 |
| Holidaymaker App Ltd | Information & communication | 2020 |
| Holland Energy Solutions Limited | Mining & quarrying | 2010 |
| Holland Street Design Limited | Wholesale & retail | 2015 |
| Hollands Farms Dorchester Limited | Agriculture & fishing | 2007 |
| Hollcomm Services Limited | Professional & scientific | 2019 |
| Holleyoak Limited | Professional & scientific | 2012 |
| Hollis Mead Farms LLP | | 2018 |
| Holt Lane Holdings Ltd | Agriculture & fishing | 2025 |
| Holzwickede Court (Block a) RTM Company Limited | Households | 2020 |
| Holzwickede Court (Block B) RTM Company Limited | Households | 2020 |
| Homefield Farm Vets Ltd | Professional & scientific | 2024 |
| Homes Dorset Limited | Real estate | 2018 |
| Honey Asset Finance Ltd. | Financial services | 2017 |
| Honey Commercial Finance Ltd | Real estate | 2020 |
| Honey Finance Limited | Financial services | 2026 |
| Honey Works Ltd | Education | 2020 |
| Hope & Glory Forces Wear & Gifts Limited | Manufacturing | 2023 |
| Horizon LP Ltd | Wholesale & retail | 2025 |
| Horizons Management Company (Weymouth) Limited | Households | 2005 |
| Horserenity Community Interest Company | Health & social care | 2017 |
| Hosford Farms Limited | Agriculture & fishing | 2026 |
| Hotline Ring Limited | Professional & scientific | 2024 |
| Hounds & Hooves Limited | Agriculture & fishing | 2016 |
| Hounds and Hooves Dog Training and Behaviour Ltd | Other services | 2026 |
| House of Podiatry Ltd | Health & social care | 2011 |
| Household & Business Solutions (Dorchester) Ltd | Construction | 2017 |
| Howard Boon (Insurances)Limited | Financial services | 1964 |
| Howard Boon Insurance (Holdings) Limited | Administrative & support | 2018 |
| Howard's Flooring Limited | Wholesale & retail | 2019 |
| Howman Books Limited | Information & communication | 2013 |
| HR & Training Doctor Ltd | Professional & scientific | 2015 |
| HR Lifeline Limited | Professional & scientific | 2013 |
| HRA Consulting Limited | Professional & scientific | 2011 |
| HS Coaching Ltd | Health & social care | 2024 |
| Hubbub Sports Limited | Information & communication | 2015 |
| Hudson & Flowerdew Ltd | Administrative & support | 2013 |
| Hudsons Developments Limited | Other services | 2004 |
| Humble Beginnings Counselling Ltd | Health & social care | 2026 |
| Humphries Kirk Services Limited | Extraterritorial | 2004 |
| Hunot Property Ltd | Construction | 2017 |
| Hunts Coffee Creamers Ltd | Wholesale & retail | 2021 |
| Husky Electricals Ltd | Energy | 2023 |
| Hutchins Property Finance Limited | Financial services | 2026 |
| Huxtable & Co Joinery Ltd | Manufacturing | 2020 |
| HY. Duke & SON Limited | Wholesale & retail | 1999 |
| Hybrid Building Products Ltd | Wholesale & retail | 2022 |
| Hyde Environmental Recycling Limited | Water & waste | 2003 |
| Hydr Group Limited | Arts & recreation | 2024 |
| Hyphon Sports Ltd | Arts & recreation | 2022 |
| I S Griffiths Associates Limited | Administrative & support | 2011 |
| I9 Ltd | Professional & scientific | 2021 |
| IAN Parker Trading Limited | Other services | 1994 |
| Ibuild Dorset Ltd | Construction | 2025 |
| Icentric Systems Limited | Information & communication | 2010 |
| Idealastic Ltd | Arts & recreation | 2022 |
| IEM Property Care Limited | Administrative & support | 2026 |
| IEM Property Services Ltd | Administrative & support | 2025 |
| Ifacial Limited | Other services | 2023 |
| Iform Buildings Limited | Construction | 2014 |
| Igloo Mortgage Limited | Financial services | 2020 |
| Ignition House Ltd | Professional & scientific | 2009 |
| II Property Limited | Real estate | 2022 |
| Ilchester Estates | Construction | 1971 |
| Ilchester Farms Ohio Limited | Agriculture & fishing | 2014 |
| Ilchester Trustee Company Limited | Administrative & support | 2002 |
| Image-In-Nation Limited | Administrative & support | 2015 |
| Imagine Dressage Limited | Arts & recreation | 2016 |
| IML (UK) Ltd | Professional & scientific | 2013 |
| IMM Music Ltd | Administrative & support | 2022 |
| Impiric Ltd | Information & communication | 2026 |
| IN the Summertime Limited | Arts & recreation | 2020 |
| In-N-Up Ltd. | Administrative & support | 2024 |
| Inca Alpaca Limited | Agriculture & fishing | 2005 |
| Independent Custody Visiting Association | Other services | 2013 |
| Indian Nights (Dorchester) Ltd | Hospitality | 2024 |
| Indikate Limited | Professional & scientific | 2011 |
| Infleet Limited | Wholesale & retail | 2004 |
| Inglewood 54 Management Limited | Households | 2000 |
| Inguardian Ltd | Real estate | 2022 |
| Inn Toxicating Limited | Hospitality | 2013 |
| Inneventive Limited | Wholesale & retail | 2001 |
| Innovations-Tech Ltd | Professional & scientific | 2008 |
| Inprove Limited | Professional & scientific | 2017 |
| Insere Ltd | Real estate | 2022 |
| Insource Legal Limited | Professional & scientific | 2014 |
| Inspirational Properties ( Dorset) Ltd | Real estate | 2025 |
| Inspired Home Improvements Limited | Construction | 2001 |
| Inspiring Heritage Ltd | Manufacturing | 2007 |
| Inspiro Capital Limited | Financial services | 2019 |
| Insync Contract Management Limited | Construction | 2024 |
| Insync Property Limited | Construction | 2014 |
| Integrated Defence Solutions Ltd | Professional & scientific | 2025 |
| Integrated Panel Technologies Ltd | Construction | 2025 |