| Middle Farm Enterprises Limited | Agriculture & fishing | 2022 |
| Middleton Care Limited | Health & social care | 2007 |
| Middleton Forge Limited | Wholesale & retail | 2002 |
| Middleton in Teesdale Farmers' Mart Limited(The) | Professional & scientific | 1924 |
| Middleton in Teesdale Fish & Chip Shop Limited | Hospitality | 2013 |
| Middleton Plus Development Trust | Other services | 1998 |
| Middy Media Limited | Information & communication | 2020 |
| Milestone X Limited | Professional & scientific | 2025 |
| Milleview Properties Limited | Real estate | 2015 |
| Mitchell Digital Ltd | Information & communication | 2021 |
| MJQ Integrity Services Limited | Information & communication | 2013 |
| Mmtqs Limited | Professional & scientific | 2025 |
| Moments Cafe Limited | Hospitality | 2018 |
| Mondeor Leach Associates Limited | Professional & scientific | 2025 |
| Money Savings Matter Limited | Wholesale & retail | 2019 |
| Moodylift Ltd | Wholesale & retail | 2019 |
| Moor Road Consulting Limited | Information & communication | 2023 |
| MP Windscreens Limited | Wholesale & retail | 2025 |
| MUD & More C.I.C. | Arts & recreation | 2024 |
| N.E.T. Waterjet Limited | Administrative & support | 2017 |
| Nabra Tech Limited | Information & communication | 2020 |
| Namens Leases Farm Limited | Agriculture & fishing | 1973 |
| National Espresso Ltd | Hospitality | 2017 |
| Natural Capital Estate Ltd | Professional & scientific | 2024 |
| NDL Vehicle Management Limited | Wholesale & retail | 2015 |
| Neds in FS Limited | Administrative & support | 2023 |
| NET Zero First Limited | Energy | 2017 |
| New Conversation Limited | Extraterritorial | 2013 |
| New Leaf Property Solutions Ltd | Real estate | 2019 |
| New Ozzy's Pizza Ltd | Hospitality | 2023 |
| Nexaro Labs Limited | Wholesale & retail | 2025 |
| Nice Cottages Ltd | Real estate | 2018 |
| Niche Inspired Limited | Wholesale & retail | 2013 |
| Nordtech Limited | Administrative & support | 2025 |
| North East Audiology Ltd | Wholesale & retail | 2021 |
| North ROW Legal Ltd. | Professional & scientific | 2017 |
| Northenstar Plumbing & Construction Ltd | Construction | 2026 |
| Northern Transport Solutions Limited | Transport & logistics | 2022 |
| Northern Vestibular & Balance Clinic Limited | Health & social care | 2025 |
| Nursery Garage Ltd | Wholesale & retail | 2011 |
| Nuzzles Limited | Wholesale & retail | 2023 |
| Obsidian Motor Company Ltd | Wholesale & retail | 2025 |
| Office Ready Technology Limited | Information & communication | 2019 |
| Old School Plumbing Limited | Construction | 2003 |
| Olovus Limited | Professional & scientific | 2020 |
| Omega Golf Ltd | Construction | 2021 |
| One-Louder Music Ltd | Administrative & support | 2006 |
| Open Refinement Ltd | Information & communication | 2018 |
| Open Refinement Property Ltd | Real estate | 2022 |
| OUT and OUT Marketing Ltd | Professional & scientific | 2023 |
| Oxford Aesthetics (North) Limited | Health & social care | 2018 |
| P & M Projects Limited | Education | 2016 |
| P & P Potatoes Ltd | Wholesale & retail | 2019 |
| P Lucky House Limited | Hospitality | 2016 |
| P S Wardle Ltd | Transport & logistics | 2016 |
| P&K Construction (Holdings) Ltd | Manufacturing | 2018 |
| P&K Fabrications Limited | Manufacturing | 2019 |
| P&S Teesdale Ltd | Hospitality | 2021 |
| P. Wilson Paving Contractors Limited | Construction | 2011 |
| PAPER2PLASTIC Ltd | Real estate | 2025 |
| PAR Design & Build Services Limited | Professional & scientific | 2012 |
| Paracletos Trading Ltd | Hospitality | 2024 |
| Patersons Couriers Ltd | Transport & logistics | 2025 |
| Peacock Property Developments Limited | Real estate | 2018 |
| Perfect Print and Promotions Limited | Manufacturing | 2020 |
| Peritum Digital Limited | Administrative & support | 2021 |
| Permax Recruitment Limited | Administrative & support | 2025 |
| Pet Go Ltd | Wholesale & retail | 2019 |
| Peter Sedgewick Ltd. | Construction | 2011 |
| Peters Cafe N Ltd | Hospitality | 2026 |
| Pharmassure International Limited | Public administration | 2012 |
| Philip Orton Limited | Construction | 2013 |
| Phillip Holden (Rural) Limited | Wholesale & retail | 2005 |
| Pinnacle Logistics Limited | Transport & logistics | 2019 |
| Pinnacle Packaging & Compliance Ltd | Information & communication | 2026 |
| PJM Transport Limited | Extraterritorial | 2023 |
| Pkamt Properties Ltd | Real estate | 2026 |
| PMR Groundworks Limited | Construction | 2012 |
| Podiatry & Legal Partnership LLP | | 2023 |
| Polychrome DSP Limited | Information & communication | 2022 |
| Portabello Joinery Ltd | Wholesale & retail | 2020 |
| Potts Groundwork Solutions Ltd | Construction | 2022 |
| Praeluceo Estates Limited | Real estate | 2022 |
| Praeluceo Group Limited | Administrative & support | 2000 |
| Praeluceo Property Limited | Administrative & support | 2022 |
| Precision Craftsmanship Ltd | Construction | 2023 |
| Premcor Estates Ltd | Real estate | 2012 |
| Prism Construction Consultants Ltd | Professional & scientific | 2025 |
| Prodigy Properties Ltd | Real estate | 2019 |
| Profit Flow Limited | Professional & scientific | 1991 |
| Prudentia-One Limited | Information & communication | 2006 |
| Pujara Trading Limited | Hospitality | 2020 |
| Pure Gold Hair Supply Limited | Other services | 2023 |
| Purkiss Property Solutions Ltd | Real estate | 2026 |
| Q.S.C.S. Limited | Extraterritorial | 2005 |
| QP Release Services Limited | Professional & scientific | 2026 |
| R & D Gregory Limited | Wholesale & retail | 2002 |
| R a Groundworks Ltd | Construction | 2023 |
| R C P B Property Limited | Real estate | 1995 |
| R J Dodd Farming Limited | Agriculture & fishing | 2017 |