| Chrelvzuer Ltd | Administrative & support | 2021 |
| Chris Baylis Associates Ltd | Professional & scientific | 2006 |
| Chromaudio Limited | Professional & scientific | 1986 |
| Civil Engineering Contracts Limited | | 1966 |
| Clavering Holdings Limited | Financial services | 2022 |
| Clavering Management Limited | Real estate | 2004 |
| Clelands (Successors) Limited | | 1932 |
| Clockwork Audio Visual Limited | Wholesale & retail | 1998 |
| Cloncrest Motors Limited | Manufacturing | 1971 |
| Cloud 9 Leisure Embroidery Specialists Limited | Wholesale & retail | 2011 |
| Cloverleaf HC Ltd | Other services | 2004 |
| Coatsworth Landscapes Limited | Administrative & support | 2004 |
| Cogito Ergo SUM Limited | Wholesale & retail | 2000 |
| Com-Spec Limited | Construction | 2003 |
| Compleat Interiors Limited | Wholesale & retail | 2007 |
| Conex Data Communications Limited | Construction | 2018 |
| Cook & Barker Inn Limited | Hospitality | 1999 |
| Coquet Cleaning Services Limited | Administrative & support | 2002 |
| Coquetdale Limited | Hospitality | 2018 |
| Corbridge Private Hire Ltd | Transport & logistics | 2001 |
| Coria Digital Ltd | Information & communication | 2025 |
| Coulson Construction Limited | Construction | 2002 |
| Cowpen Limited | Wholesale & retail | 2007 |
| Cowpen News Ltd | Wholesale & retail | 2003 |
| Cramlington Garages Limited | Wholesale & retail | 1991 |
| Crawford Higgins Associates Limited | Construction | 2001 |
| Crown & Anchor Hotel | | 2002 |
| Culpitt Limited | Manufacturing | 1931 |
| Curry and Mcqueen | | 1990 |
| Cussins Homes Limited | Financial services | 2025 |
| Cydonia Investments Limited | Financial services | 2025 |
| Cygnus Support Limited | Health & social care | 2006 |
| D M P Systems Limited | Information & communication | 1998 |
| D.P. Builders Limited | Construction | 1977 |
| D.Rose Computer Consultants Limited | | 1985 |
| Daikin Applied (UK) Limited | Manufacturing | 1998 |
| Davison Blackett Limited | Real estate | 2001 |
| Deacon Family Investment Company Limited | Construction | 2023 |
| Debdon Falls (Rothbury) Management Company Limited | Households | 2024 |
| Decopac (UK) Limited | Wholesale & retail | 1940 |
| Deepdegree Limited | Financial services | 2002 |
| Dinsdale Residential Ltd | Real estate | 2023 |
| Dixon & Baston Limited | Manufacturing | 2003 |
| DJ ORD & Sons | | 2002 |
| Dobsons Design Limited | Professional & scientific | 2004 |
| Dog Friendly Staycations Limited | Hospitality | 2021 |
| Doonan Architects Ltd | Professional & scientific | 1997 |
| Dormane Holdings Limited | Transport & logistics | 2022 |
| Dorvic Ltd | Households | 2018 |
| Douds Property Investments Ltd | Real estate | 2024 |
| Dyvels Home Limited | Wholesale & retail | 2013 |
| E.S.B. Roofing Limited | Construction | 2003 |
| East Roddam Estate Limited | Agriculture & fishing | 2022 |
| Eccleston Park (Backworth) Management Company Limited | Households | 2024 |
| Eggcel Farming Limited | Agriculture & fishing | 2018 |
| Elpha Lodge Residential Care Home Limited | Health & social care | 1997 |
| ERP Consultancy Services Limited | Professional & scientific | 2020 |
| Evans Optometrists Limited | Health & social care | 2007 |
| Everitt & Marshall Limited | Wholesale & retail | 1979 |
| Exmp UK Ltd | Professional & scientific | 2016 |
| F Southern Limited | Construction | 2010 |
| Fallodon Management Co Ltd | Agriculture & fishing | 2010 |
| Fergyprops Limited | Financial services | 2006 |
| Finalcertain Property Management Limited | Real estate | 1996 |
| Financial Direction (Northumberland) Limited | Financial services | 2004 |
| Financially Sound Limited | Financial services | 2007 |
| Finest Property Holdings Limited | Financial services | 2023 |
| Fivecall Limited | Professional & scientific | 1984 |
| Fleur DE Sante Limited | Extraterritorial | 1996 |
| Flowers by Julie Limited | Wholesale & retail | 2004 |
| G & S Mackenzie Ltd | Agriculture & fishing | 2004 |
| G T Culpitt & SON (Holdings) Limited | Professional & scientific | 1988 |
| G. Rutherford & Co. Limited | Wholesale & retail | 1936 |
| G.K. Jackson & Sons (Recovery Services) Limited | Wholesale & retail | 1964 |
| G.R. Proudlock Limited | Wholesale & retail | 1975 |
| G.S Environmental Ltd | Water & waste | 2005 |
| Galleria Retail Limited | Wholesale & retail | 2003 |
| GAN Canny Ltd | Manufacturing | 2021 |
| Gaprigg Property Limited | Construction | 2024 |
| Garfield Executive Travel Ltd | Transport & logistics | 2008 |
| Geoff Forth Ltd | Professional & scientific | 2001 |
| Gilchrist's Confectionery Limited | Other services | 2001 |
| Gott Technical Services Limited | Manufacturing | 1982 |
| Grab and Away NCE Aggregates Ltd | Transport & logistics | 2024 |
| Grainger (Commercial Developments) Limited | Construction | 1990 |
| Grainger Developments (North-East) Limited | Construction | 1977 |
| Green & Prescott Limited | Construction | 2002 |
| Green Leaf Recycling Ltd | Water & waste | 2010 |
| Gregson & Co.Limited | | 1923 |
| Groomers of Ashington Limited | Other services | 2002 |
| GRP Groundworks Limited | Construction | 2006 |
| H Duckworth Limited | Other services | 2002 |
| H J Wilson Ltd | Professional & scientific | 2012 |
| H.M.L. Limited | Hospitality | 1985 |
| Hadrian FIC Limited | Financial services | 2024 |
| Hags Holdings Limited | Financial services | 2024 |
| Haltwhistle Film Project Limited | Information & communication | 2002 |
| Haltwhistle Little Star Pre-School | Education | 2003 |
| Hamish Hall Ltd | Professional & scientific | 2006 |
| Hardy Sorensen Limited | Hospitality | 2002 |