| L Dodson QA Ltd | Professional & scientific | 2025 |
| L P Podiatry Ltd | Health & social care | 2026 |
| L Reeve Services Limited | Construction | 2025 |
| L&D Admin and Accounts Ltd | Professional & scientific | 2022 |
| L.B. Electrical Installation Services Ltd | Professional & scientific | 2013 |
| LA Engineering Northeast Limited | Professional & scientific | 2018 |
| Lagom Social Ltd | Arts & recreation | 2025 |
| Laing-Taylor Services Limited | Construction | 2025 |
| Lake Resources Ltd | Professional & scientific | 2021 |
| Lake Sky Trading Ltd | Wholesale & retail | 2025 |
| Landscape Supply Hub Ltd | Wholesale & retail | 2022 |
| Lavan Dementia Care Services Limited | Health & social care | 2023 |
| Lawn Enforcement Garden Services Ltd | Administrative & support | 2020 |
| Lawson & Marley Limited | Other services | 2017 |
| LC Trading (NE) Limited | Wholesale & retail | 2023 |
| LD Thorpey Ltd | Construction | 2025 |
| Ldkb Skelton Limited | Hospitality | 2025 |
| Ledbury Groundworks Limited | Construction | 2023 |
| LES Energy Services Limited | Mining & quarrying | 2025 |
| Letaway Ltd | Households | 2020 |
| Leven Property Services Ltd | Construction | 2021 |
| LFM Financial Ltd | Financial services | 2025 |
| LFT Instrument Consultancy Ltd | Professional & scientific | 2025 |
| Lightfoot Consulting Ltd | Information & communication | 2017 |
| Lime Street Recruitment Limited | Administrative & support | 2020 |
| Linnear Clothing Ltd | Manufacturing | 2025 |
| Little Acorn Property Investment Ltd | Real estate | 2018 |
| Little Buddies Childcare Ltd | Education | 2018 |
| Little Pearl Beauty Ltd | Other services | 2020 |
| Little Victories Marketing Limited | Professional & scientific | 2021 |
| LMR Commercial Services Limited | Professional & scientific | 2014 |
| Loftus Heavy Lift Consultants Limited | Professional & scientific | 2012 |
| Lofty Engineering (NE) Limited | Professional & scientific | 2013 |
| Logistics & Promotional Services Limited | Administrative & support | 2008 |
| Lone Star Property Solutions Ltd | Real estate | 2020 |
| Lone Star Ssas Holdings Limited | Real estate | 2021 |
| Lotus Cabling and Plant Limited | Construction | 2018 |
| Lotus Power Limited | Construction | 2026 |
| Luke Perry Industrial Services Limited | Manufacturing | 2024 |
| Lulah BLU Ltd | Wholesale & retail | 2019 |
| Luxe Bespoke Lighting Ltd | Wholesale & retail | 2024 |
| Luxe Limpia Ltd | Administrative & support | 2023 |
| M & G Exley Limited | Financial services | 2025 |
| M & S Car and Commercial Services Ltd | Transport & logistics | 2023 |
| M J Rhucroft Contracting Ltd | Construction | 2024 |
| M J Rhucroft Properties Ltd | Hospitality | 2026 |
| M&H Facilities Management Ltd | Administrative & support | 2024 |
| M. R Watson Ltd | Construction | 2023 |
| M.Stevenson Ltd | Professional & scientific | 2025 |
| Mabo Refrigeration Ltd | Energy | 2019 |
| Macey Brown Guisborough Ltd | Hospitality | 2017 |
| Mains Property Investments Ltd | Real estate | 2021 |
| Manor Garth Management Limited | Households | 2003 |
| Mark Cresswell Joinery Limited | Construction | 2016 |
| Market Place Food (NE) Ltd | Hospitality | 2025 |
| Marshall and Sons Building Limited | Construction | 2025 |
| Mary Barbers Ltd | Other services | 2024 |
| Matthew Chamberlain Limited | Information & communication | 2025 |
| Maximum Ltd | Other services | 2024 |
| Maximum Potential Sports Management Agency Ltd | Other services | 2024 |
| Mayfair Close Protection Limited | Administrative & support | 2025 |
| MB Inspection Services Limited | Construction | 2025 |
| MC Safety Ltd | Professional & scientific | 2026 |
| Mcja Limited | Construction | 2019 |
| Mclaren Architecture Ltd | Administrative & support | 2017 |
| Mclean Cleans Launderette Ltd | Administrative & support | 2022 |
| MD Mobility Ltd | Wholesale & retail | 2007 |
| ME Hospitality Limited | Hospitality | 2025 |
| MEI WEI Yuan Ltd | Hospitality | 2024 |
| MEP CAD Services Limited | Professional & scientific | 2008 |
| Mesut Barber Services Limited | Other services | 2021 |
| Mezzoforte Creative Ltd | Education | 2022 |
| Mfje Property Ltd | Real estate | 2024 |
| Michael Robinson Estimating Services Ltd | Professional & scientific | 2025 |
| Middle Media Ltd | Professional & scientific | 2020 |
| Millennium Wood (Castleton) Ltd. | Arts & recreation | 2023 |
| Mimir Consultancy Ltd | Professional & scientific | 2012 |
| Mjbunn Services Ltd | Administrative & support | 2026 |
| Mjia Engineering Limited | Professional & scientific | 2024 |
| Mkrf Holdings Ltd | Financial services | 2025 |
| Modspace Limited | Construction | 2019 |
| Molly York Limited | Real estate | 2007 |
| Morgan Autosalvage Limited | Water & waste | 2021 |
| Mountain Electrical Limited | Professional & scientific | 2024 |
| Mountcrest Projects Limited | Professional & scientific | 2015 |
| Mower Instrumentation Services Limited | Professional & scientific | 2010 |
| Mower Properties Ltd | Real estate | 2020 |
| MS Draughting Limited | Professional & scientific | 2019 |
| MS Property Solutions Limited | Real estate | 2025 |
| Mtco Holdings Ltd | Financial services | 2025 |
| Mtec Engineering Services Limited | Professional & scientific | 2024 |
| Muir & Sons Residential Limited | Real estate | 2021 |
| My Core Wellbeing Limited | Health & social care | 2017 |
| N.D. Risk Solutions Limited | Professional & scientific | 2022 |
| N.G.P. Building Ltd | Construction | 2003 |
| NDJ Offshore Limited | Professional & scientific | 2012 |
| Neatheat Services (Plumbing & Heating) Limited | Professional & scientific | 1976 |
| Nest-Ne CIC | Education | 2025 |
| New Ingk Ltd | Other services | 2024 |
| Newbrook Resources Limited | Real estate | 2015 |