| LD Private Hire Ltd | Transport & logistics | 2019 |
| LDH Roofing and Cladding Limited | Construction | 2017 |
| Lean Logistics Solutions Limited | Professional & scientific | 2023 |
| Learn in Leaps Ltd | Education | 1996 |
| Learning Trades Ltd | Education | 2019 |
| Lees Takeaway Limited | Administrative & support | 2001 |
| Lemmik Consulting Limited | Information & communication | 2015 |
| Lettn Ltd | Information & communication | 2026 |
| Level Best Property Lettings Ltd | Real estate | 2025 |
| Level Best Tank Services Limited | Manufacturing | 2025 |
| Leven Wrought Iron & Fabrication Limited | Construction | 2010 |
| Levo Web Development Ltd | Information & communication | 2010 |
| Lewis Charles Limited | Wholesale & retail | 2025 |
| Lewis Maddison Ltd | Real estate | 2020 |
| LGT Plumbing & Property Services Limited | Construction | 2017 |
| Lhaf Limited | Professional & scientific | 2011 |
| Liberating Fitness Ltd | Professional & scientific | 2021 |
| Liberty Green (Hull) Management Company Limited | Households | 2014 |
| Liddell Hall Property & Investments Ltd | Administrative & support | 1999 |
| Lifecell Limited | Manufacturing | 2006 |
| Lifestyle Logistics (North East) Limited | Transport & logistics | 2019 |
| Lifestyle Print Ltd | Manufacturing | 2013 |
| Light & Ignite Ltd | Construction | 2021 |
| Light Nights Ltd | Financial services | 2019 |
| Liloja Limited | Real estate | 2020 |
| Linburn Homes Limited | Real estate | 2023 |
| Lister Gardens Management Company (Market Weighton) Limited | Households | 2022 |
| Little Adventure Town Ltd | Education | 2026 |
| Little Chefs, Big Chefs CIC | Education | 2016 |
| Little Sicily Bishop Auckland Ltd | Hospitality | 2024 |
| Liveco Limited | Construction | 2004 |
| LJM Renovations Limited | Construction | 2024 |
| LJW Property Management Ltd | Hospitality | 2024 |
| LME Commercial Limited | Real estate | 2025 |
| LNR Property Solutions Ltd | Real estate | 2023 |
| Loftxtensions Limited | Construction | 2018 |
| Lollipop Homes Ltd | Real estate | 2021 |
| London Lending Library (Durham) Limited | Real estate | 1935 |
| Loopy Lisa's Ltd | Hospitality | 2011 |
| Lordswood Grange Management Company Limited | Households | 2012 |
| Lorry Glory Ltd | Transport & logistics | 2017 |
| Lost Cause Club Barbering Ltd | Other services | 2026 |
| Lost Cause Club Ltd | Other services | 2025 |
| Lowe Bespoke Joinery Ltd | Manufacturing | 2022 |
| LPT Trading Ltd | Financial services | 2013 |
| LT Windows & More Ltd | Construction | 2025 |
| Ltd Fire and Security Ltd | Construction | 2025 |
| LUC Consulting Limited | Financial services | 2015 |
| Ludwell Lithium Ltd | Mining & quarrying | 2022 |
| Luke Holmes Holdings Limited | Financial services | 2025 |
| Lunar Serviced Accommodation LLP | | 2017 |
| Lunar Serviced Apartments Ltd | Real estate | 2017 |
| Luscott Ltd | Real estate | 2025 |
| Luxury Eco Country Escapes Ltd | Extraterritorial | 2021 |
| M & R Developments & Contractors Ltd | Construction | 2009 |
| M & S Waiteson Limited | Real estate | 2019 |
| M Briggs Construction Ltd | Construction | 2015 |
| M D Interior Linings Ltd. | Construction | 2010 |
| M D Wilson Engineering Ltd | Professional & scientific | 2024 |
| M H Security Consultants (NE) Limited | Administrative & support | 2026 |
| M Hutchinson Investment Ltd | Real estate | 2022 |
| M L Scott Ltd | Construction | 2012 |
| M R B Schumag Ltd | Manufacturing | 1975 |
| M Smith Properties Ltd | Real estate | 2021 |
| M&I Trans Ltd | Transport & logistics | 2023 |
| M.A.M Roofing Limited | Construction | 2007 |
| M.S. Cruddas Builders Limited | Construction | 2005 |
| MAC Heating Services Ltd | Construction | 2016 |
| MAC VI Properties Limited | Real estate | 2019 |
| Maddison Davey Holdings Limited | Construction | 2019 |
| Maddison Davey Mechanical Services Ltd | Construction | 2017 |
| Maddison Management Ltd. | Administrative & support | 2016 |
| Maddison TP Ltd | Information & communication | 2024 |
| Magnum GSI Ltd | Construction | 2020 |
| Mainsforth Subsea Ltd | Professional & scientific | 2021 |
| Malones Pizzeria Ltd | Hospitality | 2022 |
| Manickam Property Limited | Real estate | 2020 |
| Mannar Trading Limited | Wholesale & retail | 2023 |
| Manners Holdings Limited | Financial services | 2016 |
| Mannor Road Limited | Wholesale & retail | 2011 |
| Manor Food Ltd | Hospitality | 2025 |
| Manor Woodcraft Limited | Manufacturing | 2003 |
| Mantle Climbing UK Ltd | Wholesale & retail | 2015 |
| Maritime Content & Connectivity Ltd | Professional & scientific | 2022 |
| Maritime Digital Innovations Limited | Transport & logistics | 2018 |
| Mark Thompson Lifesciences Ltd. | Professional & scientific | 2015 |
| Market LAU Limited | Hospitality | 2021 |
| Market Plaice Crook 2005 Limited | Hospitality | 2005 |
| Market Street Developments Ltd | Construction | 2015 |
| Martyn Hodgson Agricultural Services Limited | Wholesale & retail | 2002 |
| Masterplating Services Ltd | Manufacturing | 2025 |
| Matthew Moore Consulting Ltd | Administrative & support | 2012 |
| Matthew Vollans Construction Limited | Construction | 2004 |
| Maulers Ltd | Arts & recreation | 2022 |
| Mazy Dribble Limited | Information & communication | 2007 |
| Mcgaswork Ltd | Construction | 2026 |
| Mcgregor Lets Ltd | Real estate | 2022 |
| Mcnay Groundworks Limited | Manufacturing | 2022 |
| Mcot for Kids Limited | Health & social care | 2019 |
| MD UK Logistics Ltd | Wholesale & retail | 2025 |