| Kimberley Care Ltd | Health & social care | 2007 |
| Kind Hearts SRI Lanka Limited | Construction | 2004 |
| Kingswood Financial Management Limited | Financial services | 2003 |
| Kingswood Lettings & Property Management Limited | Real estate | 2001 |
| Kingswood Property & Financial Services Limited | Real estate | 1999 |
| Kingsworthy Construction (Portsmouth) Limited | Construction | 2003 |
| Kintsugi-International.Com Limited | Professional & scientific | 2024 |
| Kirton Farm Nurseries Limited | Wholesale & retail | 1986 |
| Kiwi Fencing Limited | Agriculture & fishing | 2003 |
| Kliwnu Shidnkgs Limited | Wholesale & retail | 2025 |
| Knights Brown Construction Ltd | Construction | 1986 |
| Knights Brown Holdings Ltd | Professional & scientific | 2018 |
| Knights Brown Ltd | Professional & scientific | 1963 |
| KOI Konsultancy Limited | Information & communication | 2001 |
| Kraftwork Limited | Manufacturing | 2003 |
| Kustom Interiors Limited | Construction | 2006 |
| KWG Management Ltd | Real estate | 2024 |
| Kyrenia Limited | Information & communication | 1997 |
| Kyri Enterprise Ltd | Administrative & support | 2006 |
| L.A. Kattenhorn & Partners Limited | Construction | 1971 |
| L.S.Powell Accountancy Services Limited | Professional & scientific | 2003 |
| Laguna Services Limited | Construction | 2000 |
| Lambert Brothers Haulage Limited | Transport & logistics | 1960 |
| Lambert Developments Limited | Construction | 1986 |
| Lampsavers Limited | Wholesale & retail | 2006 |
| Landor (UK) Ltd | Wholesale & retail | 2003 |
| Landscape Design Partnership Limited | Professional & scientific | 1998 |
| Langstone Sailing Club Limited | Arts & recreation | 1972 |
| Langton Software Limited | Information & communication | 1987 |
| Lankester Broadcast Services Ltd | Information & communication | 2004 |
| Lankford & Sons (Fishing) Limited | Agriculture & fishing | 1978 |
| Lansing Linde Limited | Extraterritorial | 1977 |
| Lansing Linde Trifik Limited | Extraterritorial | 1967 |
| Largs Yacht Haven Limited | Arts & recreation | 1982 |
| Latham Pest Control Limited | Professional & scientific | 2007 |
| Laura Skillen Salons Limited | Other services | 2021 |
| Lauralex Limited | Information & communication | 2011 |
| Laurence Oxley Limited | Wholesale & retail | 2003 |
| Laverstoke Park Produce LLP | | 2001 |
| Lawbeck Limited | Financial services | 1999 |
| Lawrence Aviation Limited | Manufacturing | 1999 |
| LCI Industries UK Ltd | Financial services | 2017 |
| LCP Wellbeing Services Ltd | Other services | 2022 |
| LD Skin Limited | Other services | 2019 |
| Leading Development Solutions Limited | Professional & scientific | 2003 |
| Leaph Services Limited | Information & communication | 1995 |
| Leela Spa Limited | Other services | 2017 |
| Legal Philosophers Conglomerate Limited | Extraterritorial | 2006 |
| Legal Risks Consultants Limited | Financial services | 2006 |
| Legend Solutions Limited | Information & communication | 1994 |
| Legg Limited | Professional & scientific | 1998 |
| Lennel Services Limited | Construction | 2000 |
| Lennox Court Management (Southsea) Limited | Hospitality | 1984 |
| Leotronics Limited | Wholesale & retail | 1990 |
| Lesandro Ltd | Health & social care | 2014 |
| Lettingsdirect.Com Limited | Real estate | 2000 |
| Levertour Property Management Company Limited | Professional & scientific | 1992 |
| Leydene Properties Limited | Construction | 1986 |
| Liddiard Scaffolding Limited | Construction | 1997 |
| Lifeline Safety Limited | Professional & scientific | 2000 |
| Liftability Limited | Construction | 1999 |
| LIL and JIM Limited | Extraterritorial | 2016 |
| Linde Castle Limited | Extraterritorial | 1979 |
| Linde Creighton Limited | Extraterritorial | 1993 |
| Linde Heavy Truck Division Limited | Professional & scientific | 1964 |
| Linde Holdings Limited | Professional & scientific | 1966 |
| Linde Jewsbury's Limited | Extraterritorial | 1993 |
| Linde Material Handling (UK) Limited | Wholesale & retail | 1937 |
| Linde Material Handling East Limited | Extraterritorial | 1993 |
| Linde Material Handling South East Limited | Extraterritorial | 1997 |
| Linde MH UK Limited | Administrative & support | 1993 |
| Linde Severnside Limited | Extraterritorial | 1997 |
| Linde Sterling Limited | Extraterritorial | 1993 |
| Lindsay Wood and Wood Limited | Professional & scientific | 1977 |
| Linear Storage Solutions Limited | Administrative & support | 2004 |
| Linian Investments Limited | Real estate | 2003 |
| Linkrealm Limited | Wholesale & retail | 1984 |
| Lion and Bull Creative Limited | Manufacturing | 2023 |
| Lissco Holding Ltd | Financial services | 2025 |
| Little Cubs Academy Greenwich Ltd | Education | 2011 |
| Little Cubs Academy Ltd | Education | 2017 |
| Little Dean House Management Co Ltd | Households | 2006 |
| Little Learners Day Care Ltd | Health & social care | 2007 |
| Little Monkeys (Horsham) Limited | Education | 2001 |
| Little Nominee Limited | Financial services | 2021 |
| Liveagain Limited | Construction | 2007 |
| Livingstones Christian Centre Limited | Wholesale & retail | 2001 |
| Lizard Securities Limited | Real estate | 1988 |
| LK Research Services Ltd | Administrative & support | 2002 |
| Lloyd Payne & Associates Limited | Professional & scientific | 1996 |
| Locke-Scobie and Associates Limited | Professional & scientific | 2005 |
| LOF (Lymington) Ltd | Wholesale & retail | 2006 |
| Londolozi Ltd | Professional & scientific | 2017 |
| London Car Official Limited | Administrative & support | 2022 |
| London Security Group | | 2007 |
| Longeven Data Ltd | Other services | 2005 |
| Loos 2 Go Limited | Professional & scientific | 2006 |
| Lovatt Plumbing & Heating Limited | Construction | 1989 |
| Loxcius Limited | Information & communication | 2007 |
| Lucy Nails & Spa Ltd | Other services | 2026 |