| K&K Properties Ltd | Real estate | 2025 |
| K.T.K. Properties Limited | Real estate | 2003 |
| Karen ANN Limited | Administrative & support | 2022 |
| Karimba Limited | Real estate | 2024 |
| Kcke Holdings Ltd | Financial services | 2021 |
| Kelby Surfacing Ltd | Construction | 2022 |
| Kelmscott Consultancy Limited | Professional & scientific | 2016 |
| Kent Fire Brigade Limited | Extraterritorial | 2024 |
| Kentish Connect Ltd | Administrative & support | 2024 |
| Kerala Ayurveda Centre - Blackburn Ltd | Health & social care | 2010 |
| Kerala Ayurveda Centre-Walsall Limited | Health & social care | 2011 |
| Kercome Limited | Real estate | 1985 |
| Kickstart Properties Ltd | Households | 2019 |
| Kiera Pico Limited | Administrative & support | 2024 |
| KIN Restaurants Limited | Hospitality | 2011 |
| Kingfisher Independent Wealth Limited | Financial services | 2012 |
| Kleyman & Co. Solicitors Limited | Professional & scientific | 2007 |
| Kort Sport & Wellness Limited | Arts & recreation | 2026 |
| Kristian Smith Ltd | Information & communication | 2022 |
| Kyle Lafferty Limited | Other services | 2016 |
| L'Estuaire Restaurant Limited | Hospitality | 2013 |
| Laser Planet Watford Limited | Arts & recreation | 2010 |
| Lawrence 2028 Limited | Arts & recreation | 2022 |
| Leicestershire & Rutland County Football Association Limited | Arts & recreation | 1999 |
| Leisure Industries (UK) Limited | | 1986 |
| Letterbox Lettings Limited | Real estate | 2021 |
| Lewccp Limited | Real estate | 2022 |
| Libra Property Company Limited | Real estate | 2007 |
| Lightfoot International Consulting Ltd | Professional & scientific | 2018 |
| Lily J Olive Interiors Limited | Professional & scientific | 2024 |
| Lindforth Ltd | Professional & scientific | 2020 |
| Linnaeus Fine Art Advisory Limited | Other services | 2024 |
| LM11 Productions Limited | Other services | 2019 |
| LO Hairdressing Ltd | Other services | 2022 |
| Location 68 Limited | Administrative & support | 2018 |
| London Mirror Company Limited | Wholesale & retail | 1997 |
| Louisa Construction Limited | Construction | 2016 |
| LR Transportation Limited | Transport & logistics | 2012 |
| LT Exclusive Limited | Other services | 2023 |
| LT Luxury Properties Limited | Real estate | 2022 |
| Lublo Limited | Professional & scientific | 2017 |
| Lucy Hall Intimates Limited | Professional & scientific | 2018 |
| Luke Bertram Limited | Professional & scientific | 2025 |
| Luke Varney PT and Performance Limited | Arts & recreation | 2021 |
| Lukegate Limited | Real estate | 1979 |
| Lulu Restaurants Ltd | Hospitality | 2016 |
| Lundstram Properties Limited | Real estate | 2019 |
| M & R Wealth Management Limited | Financial services | 2010 |
| M & Z Perfect Ltd | Construction | 2011 |
| M. L. Copeland Building Services Limited | Construction | 2003 |
| M.I.S. Management Group Limited | | 1989 |
| M7 Property Limited | Real estate | 2019 |
| Madhavan Collecot Mcdermott Associates Limited | Professional & scientific | 1988 |
| Mahtab Hussain Ltd | Arts & recreation | 2026 |
| Manor Court (Gunnersbury Avenue) Limited | Real estate | 1995 |
| Manor LEA Management Company Limited | Households | 2000 |
| Marwood Consultants Limited | | 1985 |
| MC ELL Group Limited | Households | 1996 |
| Meadhurst Limited | Extraterritorial | 2006 |
| Meicom Ltd | Wholesale & retail | 2026 |
| Melbarn Limited | Professional & scientific | 1991 |
| Meps Enterprises Limited | Real estate | 2020 |
| MET Property Management Limited | Real estate | 2017 |
| Michael Dean Promotions Limited | Other services | 2023 |
| Midco Labels Ltd | Extraterritorial | 2012 |
| MIG6 Promotions Limited | Other services | 2022 |
| Mill Finance Limited | Financial services | 2004 |
| Mima Properties Ltd | Real estate | 2017 |
| Mindflick Holdings Limited | Other services | 2015 |
| Mindflick Ltd | Other services | 2012 |
| MJM Planning Services Limited | Professional & scientific | 2023 |
| MJT Promotions Limited | Other services | 2009 |
| Monarch Oxford Limited | Transport & logistics | 2023 |
| Moore Cat Properties Limited | Real estate | 2022 |
| Moreland Investments Limited | Real estate | 1997 |
| Morris Ejector Technologies Limited | Manufacturing | 2020 |
| Motion Chauffeurs Limited | Transport & logistics | 2020 |
| MOY Environmental Safety and Health Ltd | Professional & scientific | 2004 |
| MSM Surfacing Ltd | Construction | 2016 |
| MSP Renewable Holdings Limited | Professional & scientific | 2011 |
| Munros (Accounting Services) Limited | Professional & scientific | 2003 |
| My Virtual Financial Planner Limited | Other services | 2014 |
| Nakr Holdings Limited | Financial services | 2021 |
| Nbjr Properties Ltd | Real estate | 2024 |
| NBL Engineering Limited | Professional & scientific | 2020 |
| Nebula Cloud Solutions Limited | Information & communication | 2018 |
| Neil Graham Limited | Professional & scientific | 2000 |
| Nelldor Limited | Financial services | 2024 |
| New Image Stone Limited | Construction | 2001 |
| Newbury Insurance Consultants Limited | | 1978 |
| Newplant Timber Supplies Limited | Wholesale & retail | 1991 |
| NKX Property Ltd | Extraterritorial | 2022 |
| NO Brand London Ltd | Wholesale & retail | 2018 |
| Nobel Products Limited | | 1981 |
| North Middlesex Golf Club (1928) Limited | Arts & recreation | 1928 |
| North West Lettings Partnership LLP | | 2009 |
| Northstar Homes (Procurements) Limited | Real estate | 2017 |
| Nosredna Ltd | Real estate | 2013 |
| Novate Solutions Disaster Recovery Ltd | Construction | 2023 |
| O&A Design Ltd | Professional & scientific | 2017 |