| KCC Financial Services Limited | Financial services | 2017 |
| Kearton Crushing and Screening Limited | Mining & quarrying | 2006 |
| Kevin Richardson Properties Ltd | Extraterritorial | 2014 |
| Kingfisher Finance Limited | Financial services | 2003 |
| Kirby Developments Limited | Real estate | 1991 |
| Kookaburra Limited | Manufacturing | 1987 |
| L & a Dent (Game Dealers) Limited | Agriculture & fishing | 2007 |
| Laureate Machinery Limited | Other services | 2016 |
| Leasebase Property Management Limited | Real estate | 1994 |
| Leftbank Properties Limited | Real estate | 1990 |
| Longmill Solutions Ltd | Information & communication | 2009 |
| M.Whitfield Limited | Wholesale & retail | 1935 |
| Maddison Saunders Limited | Wholesale & retail | 2025 |
| Mark Shotton Limited | Agriculture & fishing | 2006 |
| Marley Kavelle Limited | Professional & scientific | 2007 |
| Mcauliffe & Co Limited | Other services | 2005 |
| Metal Drum Company Limited(The) | Manufacturing | 1961 |
| MID Boldon Club Limited(The) | Hospitality | 1936 |
| Mindwarp Consultancy Limited | Information & communication | 1999 |
| MJW GAS and Plumbing Services Ltd | Construction | 2015 |
| Morgan Scott Accountants Ltd | Professional & scientific | 2004 |
| MRS J & J G Gill & SON Limited | Agriculture & fishing | 2006 |
| N.W.C. Precision Engineers Limited | Manufacturing | 1989 |
| Nijjar Property Management Ltd | Real estate | 2024 |
| North East Garden Supplies Ltd | Wholesale & retail | 2020 |
| Onyx Contractors Limited | Extraterritorial | 1974 |
| Owlet Grange (Management) Limited | Hospitality | 2003 |
| P&L Asset Management Ltd | Real estate | 2026 |
| P.A.T.S. Mots (Horden) Limited | Wholesale & retail | 2006 |
| Pasta (U.K.) Limited | Manufacturing | 1990 |
| PB Fibreglass Products Ltd | Manufacturing | 2003 |
| Pekin Chef DL31DX Ltd | Hospitality | 2025 |
| Permoid Industries Limited | Manufacturing | 1991 |
| Peterlee Motor Company Limited | | 1977 |
| Peterleefour Limited | Other services | 2016 |
| Peterleethree Limited | Other services | 2016 |
| PHD Training Limited | Education | 2020 |
| Philip Coates Limited | Financial services | 2007 |
| Philips Limited | Wholesale & retail | 1993 |
| PHL Design Limited | Professional & scientific | 2005 |
| Pikestream Limited | | 1977 |
| Quicktan Sunbed Hire Limited | Other services | 2006 |
| QVS Windows & Conservatories Limited | Construction | 2005 |
| R N Simpson (Roofing) Limited | | 1986 |
| R. Hope Electrical Limited | Wholesale & retail | 1973 |
| R. Roberts Tours (Wingate) Limited | Transport & logistics | 1949 |
| R. Wearmouth Limited | Construction | 2005 |
| R.F. Nunn Limited | Manufacturing | 2005 |
| R.W. Metcalfe Limited | | 1963 |
| Rose James Finance Ltd | Financial services | 2022 |
| SA Education Consultant Ltd | Education | 2025 |
| SAI Vihaan Ltd | Wholesale & retail | 2023 |
| Saks Retail Limited | Extraterritorial | 2007 |
| Saksessories Limited | Wholesale & retail | 2007 |
| Scrapula Ltd | Wholesale & retail | 2017 |
| Seaham Harbour Golf Club Limited | Arts & recreation | 1911 |
| Sight Limited | Health & social care | 1984 |
| Smile @ West Park Ltd | Health & social care | 2006 |
| Snippersgate Motor Company Limited | | 1937 |
| Stag Tyres Limited | Wholesale & retail | 2012 |
| Star Wood (Holdings) Limited | Financial services | 1984 |
| Stephen Maude Limited | Transport & logistics | 2006 |
| Strathmore Bondgate Limited | Construction | 2006 |
| Sungy Limited | Wholesale & retail | 2025 |
| Syntech Solutions Ltd | Manufacturing | 2004 |
| Systemgrade Limited | | 1989 |
| T.Mcguire Limited | Wholesale & retail | 2011 |
| Tanfield Engineering Systems Limited | Manufacturing | 2012 |
| THE Copper Mine (Crook) Ltd | Hospitality | 2019 |
| THE Fire Centre Limited | Wholesale & retail | 2010 |
| THE Smart Ladd Leisure Company Limited | Hospitality | 2002 |
| Tiles Porcelain Holdings Limited | Wholesale & retail | 2021 |
| Tiles Porcelain Limited | Wholesale & retail | 2007 |
| Todds Highway Maintenance Limited | Construction | 1996 |
| Triple T Engineering Limited | Manufacturing | 1985 |
| United Taxis (Contracts) Ltd | Transport & logistics | 2000 |
| W & W Peeled Potatoes Limited | Manufacturing | 1994 |
| W.T.And H.Field Limited | Wholesale & retail | 1954 |
| Wareadd Limited | | 1988 |
| Waskerley Park Ltd | Agriculture & fishing | 2003 |
| Wearside Civil Engineering Limited | Construction | 2001 |
| Well Worded Ltd | Professional & scientific | 2020 |
| Wilson Optometric Services Limited | Health & social care | 2003 |
| Wolsingham and Wear Valley Agricultural Society | Arts & recreation | 2000 |
| Yargate Limited | | 1973 |