| KC (Columbia Road) Management Company Limited | Households | 2014 |
| KEM Enterprises Limited | Administrative & support | 1999 |
| Kenway Estates | Financial services | 1961 |
| Ketchup Productions Ltd | Information & communication | 2025 |
| Kevin Bevis Barbier Ltd | Administrative & support | 2016 |
| Keythorpe (Bournemouth) Management Limited | Households | 1976 |
| Kf:D Limited | Professional & scientific | 2002 |
| KFA Connect Holdings Limited | Financial services | 2020 |
| KGB Carpentry Limited | Construction | 2022 |
| Kinected Solutions Limited | Public administration | 2016 |
| Kingfisher Associates (UK) Ltd. | Information & communication | 1999 |
| Kings Courtyard RTM Company Limited | Households | 2011 |
| Kiteleys Solicitors Limited | Professional & scientific | 1995 |
| KJO Accountancy Services Limited | Professional & scientific | 2003 |
| KL Events and Consultancy Limited | Administrative & support | 2017 |
| KLR Locums Ltd | Professional & scientific | 2017 |
| Klyvorn Ltd | Wholesale & retail | 2025 |
| Knole Dene Management Company Limited | Households | 1988 |
| Kook Ltd | Hospitality | 2003 |
| L & L Nails Ltd | Other services | 2025 |
| LA Lambretta Limited | Hospitality | 2017 |
| Landmark Films Ltd | Information & communication | 2001 |
| Langdown Firs RTM Company Limited | Real estate | 2010 |
| Larasian Leisure Ltd | Hospitality | 2020 |
| Larasian Limited | Construction | 1976 |
| Latitude E & W Freehold Limited | Households | 2017 |
| Laurence Seaward Plumbing & Heating Contractors Ltd | Construction | 2020 |
| Lead Mojo Productions Limited | Information & communication | 2020 |
| Leap Innovations Ltd | Hospitality | 2020 |
| Leather Designs Ltd | Manufacturing | 2018 |
| LEE Wood Limited | Information & communication | 2018 |
| Lemonaire Events Ltd | Administrative & support | 2025 |
| Lendcourt Limited | Hospitality | 1997 |
| Lettice and Lovage Ltd | Hospitality | 2019 |
| Liguoris Catering Limited | Hospitality | 2023 |
| Limetree Solutions (UK) Ltd | Professional & scientific | 2012 |
| Lintern-Mole Leney Accountants Ltd | Professional & scientific | 2008 |
| Lionheart Squared Limited | Administrative & support | 2017 |
| Liquid Art Solutions Limited | Professional & scientific | 2021 |
| Lisci Ltd | Extraterritorial | 2021 |
| Live Native Limited | Extraterritorial | 2007 |
| Lockyer Properties Limited | Construction | 2018 |
| Long Copse Developments Ltd | Construction | 2020 |
| Love Your Hair Limited | Other services | 2025 |
| LR Plumbing Ltd | Construction | 2023 |
| LS Staging Ltd | Arts & recreation | 2025 |
| Lucy Dillon Consulting Ltd | Professional & scientific | 2021 |
| Lucy Tiffney Limited | Professional & scientific | 2019 |
| Luxury Bubble Limited | Wholesale & retail | 2019 |
| M Castle Property Maintenance Limited | Construction | 2011 |
| M.E.D.A Intl Limited | Professional & scientific | 1987 |
| M.I.C. UK Property Ltd | Real estate | 2021 |
| Machine Sales Southern Limited | Manufacturing | 1984 |
| Madar Corporation Ltd | Wholesale & retail | 2012 |
| MAN VS Horse Limited | Information & communication | 2013 |
| Manor Farm Whitsbury Limited | Agriculture & fishing | 2021 |
| Manor Quay Holdings Limited | Households | 2018 |
| Manor Wharf Holdings Limited | Households | 2023 |
| Manorhouse Developments (Pitton) Ltd | Construction | 2025 |
| Manorhouse Developments (the Green) Limited | Construction | 2025 |
| Marcus Tregoning Racing Limited | Arts & recreation | 2010 |
| Marina Towers Flat Management Company Limited | Real estate | 1986 |
| Marina Towers Freehold Company Limited | Real estate | 2022 |
| Mark and ZOE Ltd | Construction | 2023 |
| Mark Valledy Media Limited | Information & communication | 2017 |
| Markini Group Ltd | Wholesale & retail | 2012 |
| Marlott Accountants Ltd | Professional & scientific | 2023 |
| Marshall Teller Records Limited | Information & communication | 2011 |
| Martin Community Shop C.I.C. | Wholesale & retail | 2023 |
| Mavericks Tattoo Studio Ltd | Other services | 2019 |
| Mayflower Gate Residents Association Limited | Households | 1995 |
| Mayfly Holdings Ltd | Hospitality | 2018 |
| MC Groundworks Ltd | Construction | 2023 |
| Mccrae Partnership Limited | Professional & scientific | 2003 |
| Mcqueen's Civil Engineering Limited | Construction | 2009 |
| Meadowsweet Chiropractic Limited | Health & social care | 2022 |
| Meadowsweet Cottages Ltd | Real estate | 2024 |
| Measured Group Ltd | Professional & scientific | 2023 |
| Medcentres PLC | Construction | 2006 |
| Medcentres Plus Limited | Health & social care | 2012 |
| Medcentres Property Portfolio Limited | Real estate | 2000 |
| Medcentres Residential Development Limited | Construction | 2017 |
| Medterrain Holdings Limited | Financial services | 2004 |
| Meducate Modules Ltd | Education | 2024 |
| Megan Plenderleith Consulting Ltd | Professional & scientific | 2025 |
| Merrow Chase Management Company Limited | Households | 1972 |
| Methuen Drive Residents Association Limited | Households | 1977 |
| MI Concepts Limited | Professional & scientific | 2013 |
| Mighty Village Records Limited | Arts & recreation | 2010 |
| Mikindani Yacht Club Limited | Extraterritorial | 2006 |
| Millie-Boo Limited | Information & communication | 2014 |
| Mitton Flight Services Ltd | Transport & logistics | 2016 |
| MJP Autotech Ltd | Wholesale & retail | 2025 |
| MKS Carpentry & Building Ltd | Construction | 2025 |
| Modbur Ltd | Wholesale & retail | 2025 |
| Modern Windows and Conservatories Ltd | Manufacturing | 2017 |
| Modernarc Ltd. | Construction | 2000 |
| Moghul Medical Limited | Health & social care | 2013 |
| Monksmoor Ltd | Hospitality | 2017 |
| Monster Ventures Limited | Wholesale & retail | 2020 |