| Modern Architectural Stone Services Limited | Professional & scientific | 2007 |
| Moffatt's of Ashington Limited | Wholesale & retail | 1997 |
| Msny Property Ltd | Real estate | 2019 |
| Multitechnic Limited | Manufacturing | 1973 |
| Multivits Limited | Extraterritorial | 2006 |
| Murdy Limited | Hospitality | 2005 |
| Natural Capital Management Limited | Professional & scientific | 2000 |
| ND Property Construction and Development Limited | Construction | 2023 |
| NE GAS Solutions Ltd | Construction | 2019 |
| Neepa Limited | Real estate | 2020 |
| Neighbourhood Hospitality Ponteland Limited | Hospitality | 2023 |
| Nelsons (Blyth) Limited | | 1931 |
| Netherton Property Investments Limited | Real estate | 1998 |
| Netherwitton Mill Limited Partnership(The) | | 1987 |
| New Bowen Properties Ltd | Real estate | 2013 |
| New Etal Farming Company LLP | | 2008 |
| Newbiggin by the Sea Partnership | Education | 1999 |
| Newbiggin Golf Club Limited | Arts & recreation | 1904 |
| Newsham News Ltd | Wholesale & retail | 2003 |
| Newtrench Limited | Agriculture & fishing | 1986 |
| NJ & JA Algar Properties LLP | | 2007 |
| NKS Cleaning Services Ltd | Administrative & support | 2023 |
| NMD Holding Limited | Financial services | 2023 |
| North East Care Management Limited | Health & social care | 2004 |
| North East Vehicle Solutions Limited | Wholesale & retail | 2005 |
| North Eastern Bricks (Bedlington) Limited | | 1934 |
| Northern Structures Ltd | Construction | 1976 |
| Northumberland Enterprise Holdings Limited | Financial services | 2020 |
| Northumberland Goldsmiths Limited | Manufacturing | 2000 |
| Northumberland Investment & Real Estate Development (Nird) Limited | Construction | 2024 |
| Northumberland Referrals Limited | Professional & scientific | 2026 |
| Northumberland Wills & Probate Ltd | Professional & scientific | 2017 |
| Northumbria Floor Covering Services Ltd | Construction | 2003 |
| Northumbria Payroll Solutions Ltd | Professional & scientific | 2007 |
| Northumbrian Distribution Limited | Wholesale & retail | 2019 |
| Northumbrian Trust Day Nurseries Limited | Education | 1996 |
| NOT Just Property Group Ltd. | Real estate | 2021 |
| Nu-Heat (North East) Ltd | Construction | 2004 |
| Ocean Properties (North East) Limited | Real estate | 2005 |
| Office & Reception Planters Limited | Manufacturing | 2006 |
| Optimation Limited | Manufacturing | 1999 |
| Oscar Constructions Limited | Construction | 2004 |
| Oswald Hughes Electricals (North East) Limited | Financial services | 2024 |
| Otter Arable Limited | Agriculture & fishing | 1998 |
| Overdrive (North East) Limited | Wholesale & retail | 2007 |
| Pacific Coast Property Limited | Real estate | 2022 |
| Padon Contracts Limited | Construction | 2002 |
| Parnell Plus Ltd | Wholesale & retail | 2020 |
| Paul Wilson Wealth Management Ltd | Financial services | 2025 |
| PCB Inspection Services Limited | Professional & scientific | 2004 |
| Pensave Limited | Professional & scientific | 2005 |
| People and Drugs Ltd | Education | 2006 |
| People-Centric Associates Limited | Professional & scientific | 2007 |
| Persistence Fitness Ltd | Arts & recreation | 2015 |
| Peter Weldon & Co Limited | Professional & scientific | 2004 |
| Pharma Nord (UK) Limited | Wholesale & retail | 1988 |
| Pipeflex Systems Ltd | Manufacturing | 2019 |
| Pixel Zone Ltd | Wholesale & retail | 2013 |
| Plastifab Limited | Manufacturing | 2007 |
| Ponteland Rugby Football Club Limited | Arts & recreation | 2010 |
| Port Brae Wealth Management Limited | Financial services | 2019 |
| Portia of Poole Limited | Agriculture & fishing | 2003 |
| Poster Identity Limited | Professional & scientific | 2003 |
| Power + Energy Associates Limited | Professional & scientific | 1997 |
| Precision Hydraulic Cylinders (UK) Limited | Manufacturing | 2001 |
| Pricewatch Supermarket Limited | Real estate | 1999 |
| Prisma Audio & Production Ltd | Information & communication | 2018 |
| Pro Scaffolding Services Ltd | Construction | 2005 |
| Punton's Footwear Limited | Wholesale & retail | 2003 |
| Purdy Lodge Limited | Hospitality | 1992 |
| Quantis Limited | Professional & scientific | 2004 |
| Quattro Fratelli (Northumberland) Limited | Hospitality | 2023 |
| QW Property Limited | Real estate | 2018 |
| R and R Hands Road Transport Limited | Transport & logistics | 2005 |
| R Havery & Co Limited | | 1974 |
| R&S White Limited | Professional & scientific | 2007 |
| R. & W. Dinning Limited | Agriculture & fishing | 2006 |
| R.D. Drilling Limited | Construction | 2006 |
| R.Green & SON Ltd | Wholesale & retail | 2004 |
| R.L. Smith & Sons Limited | Administrative & support | 2001 |
| RCL Development Holdings Ltd | Construction | 2018 |
| RD IT Consulting Limited | Information & communication | 2007 |
| Ready 2 LET (Properties) Limited | Real estate | 2004 |
| Renolit UK Limited | Manufacturing | 1925 |
| Renton Highlaws Limited | Agriculture & fishing | 2018 |
| RMP Investments Limited | Construction | 2007 |
| Road Link (A69) Holdings Limited | Transport & logistics | 1995 |
| Road Link (A69) Limited | Transport & logistics | 1995 |
| Road Link Limited | Professional & scientific | 1995 |
| Robert Kirkland (Blyth) Limited | Construction | 1973 |
| Robertson Lumley & Company Limited | Real estate | 1915 |
| Rundot Limited | Financial services | 1989 |
| Ryder Design & Build Ltd | Construction | 2023 |
| S & L Wild (Construction Services) Ltd | Construction | 2005 |
| Saffron Bidco Limited | Financial services | 2019 |
| Saffron Midco 1 Limited | Financial services | 2019 |
| Saffron Midco 2 Limited | Financial services | 2019 |
| Salem Tube Bending Limited | Professional & scientific | 2000 |
| Salem Tube International Limited | Manufacturing | 1993 |
| Sandco F.P.S. Limited | Administrative & support | 1999 |