| Jasper International Property Investment Ltd | Real estate | 2024 |
| Jays Court Freehold Limited | Households | 2010 |
| JB 360 Limited | Information & communication | 2025 |
| JB Associates (Construction Consultants) Limited | Professional & scientific | 2007 |
| JC of Lymington Limited | Other services | 2018 |
| Jcracingcharts Ltd | Arts & recreation | 2025 |
| Jennifer Boon Coaching and Consulting Limited | Professional & scientific | 2012 |
| Jennifer Whitworth Ltd | Professional & scientific | 2021 |
| Jeremy Arnold Ltd | Construction | 2015 |
| Jeremy Elliott Marine Design Limited | Arts & recreation | 2008 |
| Jeremy Rogers Limited | Manufacturing | 2001 |
| Jerome Russell Limited | Wholesale & retail | 2011 |
| Jerry Davies Planning Consultancy Limited | Professional & scientific | 2018 |
| Jessica DA Cunha Interiors Ltd | Professional & scientific | 2017 |
| Jezateza Ltd | Wholesale & retail | 2022 |
| JHF Holdings Limited | Real estate | 2017 |
| Jhjw Consulting Ltd | Information & communication | 2016 |
| Jimpa Creative Ltd | Professional & scientific | 2021 |
| JJ Media Agents Ltd | Professional & scientific | 2025 |
| JJB Signs Ltd | Manufacturing | 2015 |
| JL Yachts Ltd | Professional & scientific | 2023 |
| Jmbh Developments Limited | Construction | 2020 |
| JMRC65 Limited | Financial services | 2024 |
| JOE Bear Limited | Extraterritorial | 2003 |
| JOE Hopker Hair & Make-Up Limited | Other services | 2007 |
| John Gray & Co. LLP | | 2008 |
| John the Footman Ltd | Other services | 2013 |
| Jojo Pilates Ltd | Arts & recreation | 2026 |
| Joniskelis Ltd | Transport & logistics | 2019 |
| JP Civil Engineering Ltd | Construction | 2025 |
| JP Plumbing & Heating (Hampshire) Ltd | Construction | 2017 |
| JP72 Limited | Information & communication | 2012 |
| JPA Support Limited | Professional & scientific | 2002 |
| JRC Homes Limited | Real estate | 2020 |
| JRH Lymington Limited | Construction | 2025 |
| JRS Metal Recycling Ltd | Wholesale & retail | 2025 |
| JS Financial Consulting Limited | Professional & scientific | 2024 |
| Jsak Holdings Limited | Real estate | 2018 |
| Jtwd Holdings Limited | Real estate | 2021 |
| Juicing the Lemon Ltd | Professional & scientific | 2017 |
| Julia Carpenter Developments Limited | Administrative & support | 1985 |
| Justarrivd Ltd | Information & communication | 2016 |
| JVA Impex Ltd | Wholesale & retail | 2011 |
| K & a Property Management Ltd | Real estate | 2021 |
| K & D Crossley Limited | Information & communication | 2019 |
| K Dowse Carpentry Ltd | Construction | 2021 |
| Kandoo Holdings Limited | Financial services | 2023 |
| Kandoo Limited | Manufacturing | 1992 |
| Kandoo Property Limited | Real estate | 2023 |
| Kapable Ltd | Extraterritorial | 2020 |
| Karunā Canine Behaviour Ltd | Other services | 2021 |
| Kate Morath Limited | Information & communication | 2011 |
| Kattel Limited | Information & communication | 2009 |
| Kaze Estates Ltd | Real estate | 2024 |
| Keef Marine Ltd | Manufacturing | 2023 |
| Kels Coaching Limited | Professional & scientific | 2023 |
| Kennedy & Baxter Limited | Construction | 1972 |
| Kensington Park (Milford-On-Sea) Management Company Limited | Households | 1986 |
| Key Build Developments Ltd | Construction | 2020 |
| Keyhaven Meadow Limited | Agriculture & fishing | 2007 |
| Keyhaven Projects Ltd | Administrative & support | 2025 |
| Keyhaven Yacht Club Limited | Arts & recreation | 2009 |
| Keystone Capital Solutions Ltd | Administrative & support | 2023 |
| KH Linen Services Ltd | Other services | 2022 |
| Kifi Creative Ltd | Arts & recreation | 2004 |
| Kilomike Consultancy Limited | Professional & scientific | 2025 |
| Kim's Housekeeping Ltd | Administrative & support | 2023 |
| Kingfisher Home Care Ltd | Health & social care | 2020 |
| Kingfisher Inks and Coatings Ltd | Manufacturing | 2025 |
| Kingston Park Management Limited | Households | 1973 |
| Kiona Limited | Professional & scientific | 2021 |
| Kirton Developments Limited | Professional & scientific | 2021 |
| Kirton Property Investments Limited | Real estate | 2005 |
| Kitchen Door Refresh Ltd | Other services | 2024 |
| Kitchenmakers Limited | Manufacturing | 2011 |
| Kite Properties Limited | Construction | 1996 |
| Kitround Education CIC | Education | 2026 |
| Klpc Limited | Professional & scientific | 2011 |
| KMP Yoga Ltd | Arts & recreation | 2014 |
| Korbeyair Ltd | Transport & logistics | 2020 |
| KS Decorative Antiques Limited | Wholesale & retail | 2024 |
| KSS Development Limited | Real estate | 2010 |
| KW Performance Consulting Ltd | Professional & scientific | 2025 |
| L R Jones Scrap Metal Merchants Ltd | Water & waste | 2011 |
| L'Anza Europe Limited | Wholesale & retail | 1991 |
| L'Anza UK Limited | Professional & scientific | 2004 |
| LA Bougie UK Ltd | Wholesale & retail | 2022 |
| LA Breuille Limited | Real estate | 2005 |
| LA VIE Properties Limited | Real estate | 2006 |
| Lab-Life and Beauty Limited | Manufacturing | 2020 |
| Laboratoire Biosthetique UK Limited | Wholesale & retail | 2006 |
| Ladies That Travel Ltd | Administrative & support | 2020 |
| Ladvale Limited | Transport & logistics | 2020 |
| Lagolearn Ltd | Professional & scientific | 2016 |
| Lala Kid'Z Ltd | Wholesale & retail | 2022 |
| Landseeker Acquisitions Ltd | Extraterritorial | 2011 |
| Lanes Restaurant Limited | Hospitality | 2007 |
| Langstrath Consultancy Ltd | Construction | 2022 |
| Lantern County Limited | Information & communication | 2011 |
| Lanuthnoe Holdings Unlimited | Financial services | 2009 |