| Industrial Vibration Technology Limited | Professional & scientific | 1973 |
| International Rail Limited | Administrative & support | 1995 |
| IVC (Hampshire) Limited | Wholesale & retail | 2000 |
| J Ashburton Grenada Limited | Real estate | 2019 |
| J. a. Graham Farming Limited | Agriculture & fishing | 2006 |
| James Henry Consulting Ltd | Professional & scientific | 2023 |
| James White Fencing & Gates Limited | Administrative & support | 2011 |
| Jawibu Limited | Financial services | 2023 |
| JB Automotive Services Ltd | Wholesale & retail | 2021 |
| Jhstables Ltd | Agriculture & fishing | 2023 |
| Jmdk Finance Consulting Ltd | Professional & scientific | 2024 |
| JNM Plumbing Limited | Construction | 2020 |
| John Arlott Court Management Company Limited | Households | 2006 |
| Jonathan Didlick Golf Professional Limited | Arts & recreation | 2016 |
| Jordans Farm Equestrian Limited | Professional & scientific | 2024 |
| Journeylog Limited | Information & communication | 2009 |
| Joyce Bros Painters Ltd | Construction | 2022 |
| JPR Lighting Limited | Construction | 2007 |
| JRC Marine Ltd | Manufacturing | 2024 |
| JRS Advisory Limited | Professional & scientific | 2013 |
| JSW Planning Consultancy Limited | Other services | 2024 |
| Jtja Ltd | Professional & scientific | 2022 |
| Julie Daniels Driver Tuition Ltd | Education | 2022 |
| JVC Land Limited | Construction | 2025 |
| K.V.D. Properties Limited | Real estate | 1955 |
| Kaizen Internet Enterprises Ltd | Arts & recreation | 2006 |
| Kaliclark Limited | Administrative & support | 2023 |
| Kamash Ltd | Information & communication | 2011 |
| Kanbu Online Enterprises Limited | Wholesale & retail | 2007 |
| Karen Charlesworth Ltd | Professional & scientific | 2020 |
| Kaylie AI UK Ltd | Information & communication | 2026 |
| KEW3 Ltd | Information & communication | 2010 |
| Key Radio Networks Limited | Extraterritorial | 1991 |
| Kilmeston Management Ltd | Households | 1995 |
| Kilmeston Road (Cheriton) Management Company Limited | Households | 2006 |
| KIN Cabins Limited | Hospitality | 2025 |
| Kira's Field Limited | Real estate | 2026 |
| Kitcatt Studios LLP | | 2023 |
| Knightsbridge Farms Limited | Agriculture & fishing | 2008 |
| Krafted Media Ltd | Professional & scientific | 2025 |
| Krishnamurti Foundation Trust Limited | Education | 1972 |
| Kristian Nice Ltd | Hospitality | 2020 |
| L M Mitchell Estates Limited | Real estate | 2021 |
| L'Azure Consultancy Ltd | Construction | 2019 |
| Ladyhill Estate Limited | Manufacturing | 2020 |
| LAJ Beauty Ltd | Other services | 2024 |
| LAJ Nails Ltd | Other services | 2025 |
| Landana Limited | Real estate | 2023 |
| Landscape Associates Limited | Construction | 2005 |
| Landscape Associates Trustees Limited | Administrative & support | 2025 |
| Lankester & Crook Limited | Real estate | 1901 |
| Laurel House Projects Ltd | Wholesale & retail | 1981 |
| Lawn Envy Limited | Administrative & support | 2023 |
| Leevan Limited | Real estate | 2020 |
| Liberty Developments South Limited | Construction | 2013 |
| Little Big Giant Limited | Professional & scientific | 2013 |
| Little Cottage Stays Limited | Hospitality | 2017 |
| Little Orchard Pubs Ltd | Hospitality | 2021 |
| LMD Project Services Limited | Professional & scientific | 2013 |
| Lockaway Storage Limited | Transport & logistics | 2013 |
| Lockrose Limited | Professional & scientific | 2024 |
| Lolly Films Limited | Information & communication | 2025 |
| Long Barn Winchester Ltd. | Agriculture & fishing | 2006 |
| Lorem Skin & Body Therapy Limited | Wholesale & retail | 2013 |
| Lorunser | Financial services | 2018 |
| Luby Hart Design Ltd | Professional & scientific | 2025 |
| Lucas Publications Limited | Information & communication | 1998 |
| Lyeway Farms Limited | Professional & scientific | 1997 |
| Lyewood Horticulturists Ltd | Agriculture & fishing | 2020 |
| Lyewood Nursery (Ropley) LLP | | 2012 |
| M and R Morton Limited | Agriculture & fishing | 1998 |
| M P W Engineering Design Limited | Professional & scientific | 1998 |
| MAE Consulting Limited | Professional & scientific | 2018 |
| Maison Surveyors Ltd | Professional & scientific | 2022 |
| Majestic Software Solutions Limited | Information & communication | 2004 |
| Mamobella LLP | | 2024 |
| Mamotilda LLP | | 2024 |
| Mange 2 Deli Limited | Wholesale & retail | 2008 |
| Mange 2 Events Limited | Hospitality | 2003 |
| Mann Media Limited | Information & communication | 2002 |
| Manor Farm (Chilcompton) Limited | Real estate | 2005 |
| Maples Trading Limited | Financial services | 2021 |
| Mark & Hill Limited | Construction | 1957 |
| Marlock Homes Limited | Real estate | 2018 |
| Marshall Westbourne Limited | Financial services | 2011 |
| Martha Hollis Event Catering Ltd | Hospitality | 2023 |
| Masdupot Ltd | Real estate | 2006 |
| Master JET Limited | Construction | 1989 |
| Matthew Coles Ltd | Financial services | 2019 |
| Maytree Accounts Ltd | Professional & scientific | 2025 |
| Maze Central Limited | Administrative & support | 2016 |
| MBD Property Management Services Limited | Real estate | 2013 |
| MCC INT Ltd | Professional & scientific | 2020 |
| Mcgregor Group Limited | Financial services | 2016 |
| Mcgregor Installations Ltd | Construction | 1984 |
| Mcgregor Operations Limited | Manufacturing | 2024 |
| Mcgregor Structures Limited | Manufacturing | 2000 |
| Mcgregor Works Limited | Manufacturing | 1979 |
| MD3 Limited | Arts & recreation | 2003 |
| Medical Screening Services Limited | Professional & scientific | 1986 |