| Lakeland Holidays Ltd | Real estate | 2024 |
| Lanchester News Limited | Wholesale & retail | 2024 |
| Landdrtransport Ltd | Transport & logistics | 2024 |
| Langley Agents (Crook) Holdings Limited | Financial services | 2023 |
| Langley Agents (Crook) Limited | Financial services | 2012 |
| Lato Properties Ltd | Real estate | 2019 |
| Layfield Renewable Ltd | Energy | 2012 |
| LE DOR Consultants Ltd | Professional & scientific | 2020 |
| Leah Quality Limited | Hospitality | 2018 |
| LEE Airey Limited | Wholesale & retail | 2016 |
| Leedawn Properties Limited | Real estate | 2012 |
| Lenna Management Ltd | Professional & scientific | 2011 |
| Lifestyle Wise Ltd | Wholesale & retail | 2020 |
| Lintons Printers Limited | Manufacturing | 2001 |
| Lnpm Enterprises Ltd | Wholesale & retail | 2026 |
| Logi Personnel Ltd | Administrative & support | 2024 |
| London Healthcare and Conferences International (UK) Ltd | Professional & scientific | 2021 |
| London Lawyers Ltd | Other services | 2025 |
| Longhorn Brewery Services (NE) Limited | Manufacturing | 2021 |
| Love Efficient Homes Limited | Energy | 2020 |
| Lovely Services Limited | Public administration | 2019 |
| Lucky Red 936 Ltd | Hospitality | 2023 |
| Luka Groundworks Ltd | Administrative & support | 2026 |
| Lusotufo U.K. Ltd | Manufacturing | 1994 |
| M & PS (Properties) Limited | Real estate | 2003 |
| M D H Painting Contractors Limited | Construction | 2007 |
| M&S Logistics Consulting Ltd | Professional & scientific | 2024 |
| M.Y. Associates Limited | Professional & scientific | 2012 |
| Maddison Builders Ltd | Construction | 2025 |
| Made by Britain Limited | Professional & scientific | 2003 |
| Madesmemax Ltd | Administrative & support | 2019 |
| Magic Fade Barber(Ne) Limited | Other services | 2026 |
| Magic Property Group Limited | Financial services | 2024 |
| Magic Property Network Limited | Real estate | 2024 |
| Mapp's Mortgage & Insurance Ltd | Financial services | 2011 |
| Mapps (Crook) Ltd | Financial services | 2013 |
| Marc ROE Construction Ltd | Construction | 2023 |
| Marleys Transport NE Ltd | Transport & logistics | 2020 |
| Marshall Richards Machine Co.Limited | | 1937 |
| Master Tang Catering Ltd | Hospitality | 2026 |
| Masterson Incorperated Ltd | Other services | 2024 |
| Mcclurg Scaffolding Ltd | Administrative & support | 2009 |
| MCJ Electrical Ltd | Construction | 2022 |
| Meat & Sea Ltd | Wholesale & retail | 2024 |
| MEM Holdings Ltd | Manufacturing | 2023 |
| Metallink Fluid Power Systems Limited | Manufacturing | 1996 |
| Million Vitamins & Minerals Ltd | Wholesale & retail | 2020 |
| MJR Groundworks & Landscaping Ltd | Construction | 2023 |
| ML Dixon Plumbing & Heating Engineer Ltd | Construction | 2018 |
| MLD Renewables Limited | Manufacturing | 2022 |
| Monaghan Events Ltd | Hospitality | 2025 |
| Moonflower Genetics Ltd | Wholesale & retail | 2026 |
| Moorsynergy Ltd | Energy | 2017 |
| Moralee Farms Limited | Agriculture & fishing | 2022 |
| MPF Horse Talent Ltd | Agriculture & fishing | 2012 |
| MPW Offshore Ltd | Other services | 2025 |
| MSU Heating Solutions Ltd | Construction | 2026 |
| MW Deep Domestics Ltd | Administrative & support | 2026 |
| My UK Network Ltd | Information & communication | 2007 |
| Myers Welding Ltd | Manufacturing | 2023 |
| N & R Fencing Ltd | Manufacturing | 2023 |
| N Cook Building Contractors Limited | Construction | 2006 |
| N Herron Plumbing & Heating Ltd | Construction | 2026 |
| Naturesupplies Ltd | Extraterritorial | 2008 |
| NB Rail Care Ltd | Manufacturing | 2021 |
| Ncott FSS Ltd | Public administration | 2017 |
| Needham Engineering Consultants Limited | Professional & scientific | 2025 |
| New Little China WNN Limited | Hospitality | 2025 |
| Nikesh Ramesh Ltd | Wholesale & retail | 2018 |
| North East Poultry Ltd | Agriculture & fishing | 2015 |
| North East Towing and Recovery Ltd | Wholesale & retail | 2020 |
| North Terrace Store Ltd | Wholesale & retail | 2024 |
| Northern Exotics Ltd | Wholesale & retail | 2023 |
| Northern Junior Golf Tour Ltd | Arts & recreation | 2020 |
| Northern Lets Limited | Extraterritorial | 1999 |
| Northside Equestrian Centre Limited | Agriculture & fishing | 2002 |
| Norton Hall & Gold Limited | Real estate | 2016 |
| Overarch Services Ltd | Information & communication | 2019 |
| P & K (Cassop) Limited | Hospitality | 2024 |
| P M L Decorating Services Ltd | Construction | 2025 |
| P.A.W Decorators Ltd | Construction | 2023 |
| Padgett White Architects Limited | Professional & scientific | 2002 |
| PAF Lifting Solutions Limited | Professional & scientific | 2025 |
| Palace Yummy Limited | Hospitality | 2025 |
| Panda Express Food Ltd | Hospitality | 2024 |
| Papa Joe's Ltd | Wholesale & retail | 2020 |
| Parmoandmoreco SI Ltd | Hospitality | 2026 |
| Parrano Pizza Willington Ltd | Hospitality | 2021 |
| Party Time Hot TUB and Bar Hire Limited | Hospitality | 2022 |
| PAS Retrofit Solutions Ltd | Professional & scientific | 2021 |
| Paul Housing Ltd | Real estate | 2023 |
| Paul Wile Logistics Ltd | Transport & logistics | 2023 |
| Payroll for Pensions Limited | Administrative & support | 2016 |
| People Software Solutions Limited | Information & communication | 2024 |
| Perfect Chicken Crook Limited | Hospitality | 2024 |
| Perla Nera Limited | Hospitality | 2026 |
| PIP Rentals Ltd | Real estate | 2025 |
| Pizza Roma Crook Limited | Hospitality | 2026 |
| Pizzeria Crook Ltd | Hospitality | 2024 |
| Podiatryforyou Limited | Health & social care | 2020 |