| Link Digital Limited | Administrative & support | 2013 |
| Linton Ag-Industrial Limited | Wholesale & retail | 2005 |
| Liquidity 4 Life Limited | Information & communication | 2017 |
| Lite Bell (UK) Limited | Real estate | 2025 |
| Little Blue Van (G a) Limited | Education | 2013 |
| Little Bottle Club Ltd | Wholesale & retail | 2026 |
| Little Florence Art Limited | Arts & recreation | 2018 |
| Livanur Limited | Hospitality | 2024 |
| Live Music Photo Limited | Arts & recreation | 2015 |
| Lloyd Manex Limited | Administrative & support | 1997 |
| LM Maintenance Services Ltd | Manufacturing | 2019 |
| LM Pharma Marketing Ltd | Professional & scientific | 2016 |
| LMA Financial Solutions Limited | Professional & scientific | 2018 |
| LMC Content Ltd. | Administrative & support | 2020 |
| Load Angel Limited | Extraterritorial | 2011 |
| Loan Hunter Ltd | Professional & scientific | 2005 |
| LOC Management Ltd | Professional & scientific | 2019 |
| Local Hertford Taxis Ltd | Transport & logistics | 2021 |
| Locstock Ltd | Administrative & support | 2022 |
| Logic Electronics Limited | Wholesale & retail | 2025 |
| Logic RC Limited | Wholesale & retail | 2008 |
| Logistics Law Ltd | Education | 2025 |
| London & International Mercantile Ltd | Financial services | 1999 |
| London Fast Food Developments Limited | Hospitality | 2005 |
| London Parquet Co Ltd | Wholesale & retail | 2022 |
| London Riviera Limited | Construction | 2014 |
| London Running Physio Ltd | Health & social care | 2018 |
| Long Meadow (Watton) Management Company Limited | Administrative & support | 2000 |
| Long River (London) Limited | Administrative & support | 2020 |
| Longacre Tree Surgery Ltd | Agriculture & fishing | 2018 |
| Longbarrow Limited | Construction | 1997 |
| Longborder Holdings Limited | Real estate | 2025 |
| Longmores Law Limited | Extraterritorial | 2020 |
| Longmores Solicitors LLP | | 2013 |
| Longmuir Consultancy Limited | Administrative & support | 2025 |
| Lootpay Europe Ltd | Financial services | 2025 |
| Lord Haig Ltd | Hospitality | 2026 |
| Lord Harrison Limited | Real estate | 2023 |
| Lorensbergs Limited | Information & communication | 1999 |
| Lorne Literary Publishing Limited | Information & communication | 2024 |
| Lost IT Productions Limited | Administrative & support | 1997 |
| Lost Running Ltd | Manufacturing | 2026 |
| LOT Distribution Ltd | Wholesale & retail | 2024 |
| LOT Franchise Ltd | Other services | 2022 |
| Lotos LAB Limited | Manufacturing | 2023 |
| Loughton Music Academy Limited | Education | 2001 |
| Louis Consulting Ltd | Health & social care | 2023 |
| Louise Lawton Performing Arts LLP | | 2025 |
| Lovats Chase Management Company Limited | Other services | 2018 |
| Love Croyde Limited | Real estate | 2018 |
| Love Savvy Ltd | Professional & scientific | 2024 |
| Love Sleep Consulting Ltd | Other services | 2016 |
| Love Your Local Limited | Hospitality | 2024 |
| Lowfoam Ltd | Construction | 2024 |
| LP Fire Solutions Limited | Administrative & support | 2014 |
| LP Investments (2024) Limited | Financial services | 2024 |
| LP Pallett Ready-Mix Ltd | Manufacturing | 2014 |
| LP Reed Sales and Consultancy Ltd | Administrative & support | 2026 |
| Lp&Js Properties Limited | Real estate | 2019 |
| Lpbn Properties Ltd | Real estate | 2024 |
| LPS GB International Ltd | Administrative & support | 2025 |
| LS Environmental Ltd | Transport & logistics | 2018 |
| Lsafiresafety Ltd | Public administration | 2023 |
| LSB Property Group Ltd | Real estate | 2025 |
| LSJ Roofing Ltd | Construction | 2021 |
| Ltd Creative Print & Solutions Limited | Manufacturing | 2018 |
| Lucabella Manufacturing Limited | Manufacturing | 2021 |
| Lumi Aesthetica Limited | Arts & recreation | 2026 |
| Lusty and Bloom Ltd | Information & communication | 2021 |
| LUX Dolls Ltd | Professional & scientific | 2026 |
| LUX Products UK Limited | Wholesale & retail | 2020 |
| Lydian Care Ltd | Health & social care | 2007 |
| Lyndon Pallett (EA) Limited | Mining & quarrying | 2012 |
| Lyons Heating Engineers Limited | Health & social care | 2014 |
| Lytton Design Limited | Administrative & support | 2020 |
| Lytton Management Limited | Households | 2015 |
| M & J Property Management Ltd | Real estate | 2014 |
| M & J Transport (Hoddesdon) Limited | Transport & logistics | 2019 |
| M D Milk Services Ltd | Wholesale & retail | 2016 |
| M J D Building and Carpentry Limited | Construction | 2024 |
| M K W Consulting Limited | Information & communication | 2002 |
| M Star Graphics Limited | Administrative & support | 2003 |
| M&A Hertford Ltd | Wholesale & retail | 2018 |
| M&R Properties (2023) Limited | Real estate | 2023 |
| M. Dimond Limited | Manufacturing | 1987 |
| M.D. Electrical Company Limited | Administrative & support | 1992 |
| M.H. Goldsmith & Sons Limited | Construction | 1973 |
| M.J.L. Construction Associates Limited | Construction | 2007 |
| M.P.I. (Herts) Limited | Professional & scientific | 2003 |
| M.P.I. Limited | Administrative & support | 1992 |
| M3TRICS Ltd | Professional & scientific | 2024 |
| MAC Daddy Limited | Wholesale & retail | 2015 |
| MAC Rhythm Limited | Administrative & support | 2002 |
| MAC Securities Ltd | Professional & scientific | 2021 |
| MAC Two Engineering Limited | Real estate | 1997 |
| Macbourt Limited | Real estate | 1994 |
| Macci Construction Limited | Construction | 2021 |
| Maces Limited | Information & communication | 1996 |
| Made for Time Ltd | Wholesale & retail | 2024 |
| Madisons Engineering Ltd | Administrative & support | 2023 |