| Howland Tech Studios Ltd | Professional & scientific | 2025 |
| Htpp Ltd | Construction | 2024 |
| Hunt & Rogers Limited | Professional & scientific | 1947 |
| I AM ME Clothing Ltd | Wholesale & retail | 2022 |
| Ideal Inventories Limited | Real estate | 2011 |
| IES Fire & Security Ltd | Administrative & support | 2012 |
| IN the Hand Limited | Information & communication | 2004 |
| Informed Engineering Limited | Professional & scientific | 2013 |
| Informed Engineering Property Holdings Limited | Financial services | 2025 |
| Informed Technology Limited | Information & communication | 2025 |
| Institute of Ergonomics and Human Factors | Other services | 1985 |
| J R Beauty Services Limited | Other services | 2006 |
| J. Whelan & Sons Limited | Real estate | 1957 |
| Jaluma Property Holdings Limited | Financial services | 2025 |
| Jamaya CC Ltd | Hospitality | 2020 |
| Jamaya FS Ltd | Financial services | 2020 |
| Jamaya JC Limited | Hospitality | 2018 |
| Jenna Farmer PR Ltd | Professional & scientific | 2024 |
| Jephson Portfolio (Leamington Spa) Management Company Limited | Households | 2022 |
| Jewellery Brokers Limited | Wholesale & retail | 1987 |
| Johnson Place Management Limited | Households | 1982 |
| Johnson Properties Services Ltd | Real estate | 2025 |
| Jsnb Limited | Hospitality | 2024 |
| K D Estates Limited | Real estate | 2008 |
| K J Rodgers Limited | Professional & scientific | 2009 |
| K2JY Limited | Hospitality | 2016 |
| Kalastina (UK) Ltd | Real estate | 2025 |
| Kanda Finance Limited | Financial services | 2021 |
| KG Financial Ltd | Financial services | 2018 |
| Kissing IT Better | Health & social care | 2011 |
| Kitewinder Properties Limited | Real estate | 2013 |
| Knight Industries Three Thousand Limited | Other services | 2005 |
| Knight's Plumbing and Heating Solutions Ltd | Construction | 2021 |
| Knowsley Redevelopments Ltd | Real estate | 2020 |
| Kookaburra Property Ltd | Real estate | 2025 |
| KSJ Osborn Limited | Other services | 2013 |
| KSW (Chesterton) Limited | Real estate | 2021 |
| KSW (Evesham) Limited | Real estate | 2023 |
| KSW Brize Norton Ltd | Real estate | 2020 |
| KSW Daventry Limited | Real estate | 2024 |
| Ktmo Limited | Health & social care | 2025 |
| Kudos Manufacturing Limited | Manufacturing | 2003 |
| L and J Dale Property Developments Limited | Real estate | 2026 |
| L1L2 Property Investments Ltd | Real estate | 2026 |
| Leanne Perrins Media Limited | Information & communication | 2018 |
| Legacy Hotels 2025 Limited | Financial services | 2025 |
| Legacy Hotels Management Ltd | Hospitality | 2014 |
| Leigh Tax Ltd | Professional & scientific | 2025 |
| Leighton Hamilton Management Ltd | Real estate | 2006 |
| Leisuresec Limited | Administrative & support | 1999 |
| Let-It-Out Limited | Real estate | 2006 |
| Levy Lettings Limited | Real estate | 2019 |
| LHM NO 2 Limited | Real estate | 2019 |
| Liberty Park Management Limited | Households | 2006 |
| Licensing 182 Application Services Limited | Professional & scientific | 2022 |
| Licensing 182 Limited | Professional & scientific | 2003 |
| Lithos Group Ltd | Hospitality | 2026 |
| Liveridge Properties Limited | Real estate | 2025 |
| LME 83 Properties Limited | Real estate | 2023 |
| LOCAL148 Ltd | Hospitality | 2023 |
| Lodders Barn Ltd | Administrative & support | 2024 |
| London and Birmingham Property Holdings Limited | Financial services | 2025 |
| Longmead Developments Limited | Agriculture & fishing | 1995 |
| Longminster Limited | Professional & scientific | 1984 |
| Louis Fraser Ltd | Administrative & support | 2005 |
| Lowsonford Pies Ltd | Manufacturing | 2018 |
| Ludgate Holdings 2 Ltd | Financial services | 2019 |
| Ludgate Holdings Ltd | Construction | 2017 |
| Lythia Property Limited | Real estate | 2023 |
| Machmeric Europe Ltd | Professional & scientific | 2019 |
| Maddison Creative Limited | Information & communication | 2013 |
| Made by Etoile Ltd | Manufacturing | 2019 |
| Maia Asset Management Limited | Financial services | 2016 |
| Maia Holding Limited | Administrative & support | 2024 |
| Mantua Capital (UK) LP | | 2011 |
| Many Hands Group Ltd | Administrative & support | 2020 |
| Mark LE Serve Limited | Professional & scientific | 2012 |
| Marlbrook Developments Limited | Financial services | 2025 |
| Marta 1944 Group Holdings Limited | Real estate | 2023 |
| MAT Lodder Polo Ltd | Arts & recreation | 2010 |
| Maven Labs Ltd | Information & communication | 2021 |
| Maycroft Property Ltd | Construction | 2022 |
| MC Lettings and Property Management Limited | Administrative & support | 2025 |
| MDD (A.P.C) Limited | Professional & scientific | 2012 |
| Meadshaw Limited | Financial services | 2013 |
| Melwest Freehold Limited | Households | 1997 |
| Melwest Limited | Households | 1977 |
| Mercia Company Secretarial Services Limited | Professional & scientific | 2022 |
| Mercia Fund 1 General Partner Limited | Financial services | 1998 |
| Mercia Fund Management (Nominees) Limited | Professional & scientific | 2009 |
| Mercia Fund Management Limited | Financial services | 2009 |
| Mercia Growth Nominees Limited | Extraterritorial | 2011 |
| Mercia VCT Nominee Limited | Financial services | 2017 |
| Mermaid Studios Interactive Limited | Information & communication | 2000 |
| Metropolitan Developer Ltd | Construction | 1998 |
| MFR Medicals Ltd | Health & social care | 2019 |
| MG Energy Consulting Limited | Professional & scientific | 2019 |
| Miles Kingsley Consulting Limited | Professional & scientific | 2007 |
| MLC Holdings Ltd | Financial services | 2024 |
| Moneyinfo Limited | Information & communication | 1998 |