| Great Central Engineering Limited | Manufacturing | 1996 |
| Hangoutdoors Ltd | Arts & recreation | 2025 |
| Hannah Snellgrove Ltd | Education | 2020 |
| Harkwise Ltd | Information & communication | 2023 |
| Hayloft Properties Limited | Construction | 2021 |
| Hayter Carpets (Portland) Ltd | Wholesale & retail | 2013 |
| Haywood Estates (UK) LLP | | 2013 |
| Heli Operations Limited | Administrative & support | 2012 |
| Helidata Ltd | Transport & logistics | 2018 |
| Hepburn Building Ltd | Construction | 2024 |
| Hercoperations Ltd | Transport & logistics | 2015 |
| Heritage Fire Protection Ltd | Construction | 2016 |
| Heritage Fire Sprinklers Ltd | Construction | 2016 |
| Home Fire Sprinklers Ltd | Construction | 2016 |
| Horizon Park Limited | Construction | 2018 |
| Hyde Fabrications (Portland) Limited | Manufacturing | 2005 |
| Iapwws UK Limited | Extraterritorial | 2006 |
| Ice Ice Kayla Ltd | Wholesale & retail | 2025 |
| Ikizler Cafe Portland Limited | Hospitality | 2025 |
| Invest Automated Trading Ltd | Professional & scientific | 2025 |
| Iqrah Smart Ltd | Hospitality | 2020 |
| Island Portland Cafe Limited | Hospitality | 2025 |
| Isle of Portland Home Care Limited | Health & social care | 2026 |
| J&Lsnackshack Ltd | Manufacturing | 2025 |
| J. E. Alderton Limited | Construction | 2000 |
| Jason Anderson Artist Ltd | Arts & recreation | 2019 |
| Jasryle Enterprises Limited | Administrative & support | 2021 |
| Jecs Consulting Ltd | Professional & scientific | 2025 |
| JJ Tipple Ltd | Hospitality | 2020 |
| Jones the Pipe Limited | Construction | 2016 |
| JS Travel (Weymouth) Ltd | Transport & logistics | 2024 |
| Jurassic Aquatics Ltd | Wholesale & retail | 2023 |
| Jurassic Event Medical Ltd | Health & social care | 2024 |
| Jurassic Razor Carts Ltd | Arts & recreation | 2025 |
| Justurbiz Limited | Professional & scientific | 2006 |
| K Star Portland Barbers Ltd | Other services | 2024 |
| Kaani Ltd | Hospitality | 2020 |
| KCH Plant Services Limited | Construction | 2018 |
| Keelpulse Ltd | Information & communication | 2026 |
| Kerching Ltd | Information & communication | 2006 |
| KG GRP Roofing and Building Ltd | Construction | 2011 |
| L&D’S Corner House Inn Ltd | Hospitality | 2024 |
| L.Landscapes Ltd | Administrative & support | 2023 |
| LAG Development Ltd | Hospitality | 2015 |
| Lansdowne Hill Care Home Limited | Health & social care | 2011 |
| Launchkeen Limited | Households | 1990 |
| Learn to DO IT Limited | Information & communication | 2010 |
| Louise Scott Limited | Wholesale & retail | 2025 |
| Luremaker Ltd | Wholesale & retail | 2021 |
| M & H Cleaning Services Portland Ltd | Administrative & support | 2026 |
| M&B Marine Services Ltd | Professional & scientific | 2023 |
| M2M Conversions Ltd | Wholesale & retail | 2021 |
| Macgregor's Plumbing, Heating & GAS Limited | Construction | 2026 |
| Manor Marine UK Limited | Manufacturing | 1991 |
| Manor Sales & Lease Limited | Wholesale & retail | 2026 |
| Mariners Court Management Company Limited | Households | 1989 |
| Maritime Hotel Portland Limited | Hospitality | 2018 |
| Mckenzie Inn Ltd | Hospitality | 2025 |
| Mitchell Court Residents Ltd | Households | 2002 |
| MLK Cleans Ltd | Administrative & support | 2025 |
| Moonshine Group Ltd | Hospitality | 2025 |
| Moore GAS Plumbing & Heating Limited | Construction | 2021 |
| Moorfield Road Properties Limited | Households | 2018 |
| Morris Group Assets Limited | Financial services | 2026 |
| Morris Group Trading Limited | Real estate | 2010 |
| Move on Inns Limited | Hospitality | 2025 |
| Murray PUB Solutions Limited | Hospitality | 2025 |
| Mutton Cove Residents Ltd | Real estate | 2019 |
| My Care Manager Ltd | Professional & scientific | 2010 |
| Naseby Care Home Limited | Health & social care | 2010 |
| Navigator Business Centre Limited | Real estate | 2015 |
| Navigator Park (Management) Limited | Households | 2018 |
| NCG Developments Ltd | Construction | 2020 |
| NCG Investments Ltd | Real estate | 2019 |
| NEC (Portland) Limited | Real estate | 2007 |
| Neighbourhood Colab C.I.C. | Health & social care | 2025 |
| Neighbourhood Infection Control Solutions Ltd | Health & social care | 2025 |
| Netbox Ltd | Information & communication | 2018 |
| New Castletown Stores Limited | Wholesale & retail | 2017 |
| New Street Close Ltd | Administrative & support | 2025 |
| Oakwood Wills Limited | Professional & scientific | 2019 |
| Oceanbrake Limited | Wholesale & retail | 2019 |
| Open Doors Marketing Limited | Professional & scientific | 2014 |
| Osprey Holiday Cottages Limited | Hospitality | 2021 |
| OUT & About Community Services Community Interest Company | Health & social care | 2012 |
| Palermo Leeds LLC | | 2025 |
| Palookaville Pictures Limited | Information & communication | 1997 |
| Parkview (Portland) Management Company Limited | Hospitality | 1997 |
| Paul Cormack LLP | | 2003 |
| Paul Webb Ltd | Manufacturing | 2021 |
| Pearl Avery Ltd | Professional & scientific | 2019 |
| Pebbles Beach Floristry Ltd | Wholesale & retail | 2019 |
| Perceptive Protection Ltd | Administrative & support | 2019 |
| Pierced by Katy Ltd | Other services | 2025 |
| Pipefish Digital Marketing Limited | Information & communication | 2016 |
| Planedata Ltd | Extraterritorial | 2020 |
| Portland Alpacas Limited | Agriculture & fishing | 2019 |
| Portland Bespoke Ltd | Manufacturing | 2026 |
| Portland Bill Lighthouse Centre Limited | Arts & recreation | 2015 |
| Portland Bunkhouse Limited | Hospitality | 2024 |