| Burdon Terrace Management Company Limited | Households | 1999 |
| Butebond Ltd | Administrative & support | 2003 |
| Byron Longstaff Independent Financial Consultancy Limited | Financial services | 2003 |
| C & W Electrical & Mechanical Contractors Limited | Wholesale & retail | 1998 |
| C Appleyard Limited | Professional & scientific | 2003 |
| C Grant (Roofing and Guttering) Limited | Construction | 2007 |
| C.F. Butt & SON Ltd | Wholesale & retail | 2003 |
| Callas Services Ltd | Construction | 2003 |
| Calorplast (UK) Limited | Manufacturing | 2026 |
| Camden Fires and Pine Limited | Construction | 2003 |
| Camino Stoves Ltd | Administrative & support | 2021 |
| Canamex Properties Limited | Professional & scientific | 2003 |
| Canatrice Limited | Manufacturing | 1975 |
| Canford Audio Limited | Manufacturing | 1978 |
| Canford Group Limited | Financial services | 1996 |
| Carlton Grove Maintenance Limited | Households | 1986 |
| Castle Quays Limited | Households | 1994 |
| Castles Green Management Company Limited | Households | 1983 |
| Ccow Limited | Information & communication | 2003 |
| Cell H Seaham Garden Village (Block a) Management Company Limited | Households | 2026 |
| Cell H Seaham Garden Village (Block B) Management Company Limited | Households | 2026 |
| CG Estates Corbridge Ltd | Real estate | 2023 |
| Chambers Bottled GAS Ltd | Wholesale & retail | 2006 |
| Chapman's the Jewellers Limited | Wholesale & retail | 2003 |
| Children North East | Other services | 1906 |
| Choice Care Services Limited | Health & social care | 2002 |
| Choicepalm Limited | Hospitality | 1988 |
| Christal Clear Image Limited | Professional & scientific | 2006 |
| Christopher Matthew Limited | Health & social care | 2001 |
| Ciao Ragazzi Limited | Administrative & support | 2001 |
| CIB Construction Limited | Construction | 2002 |
| Claremont Court (Whitley Bay) Management Company Limited | Households | 1997 |
| CLG Glazing Limited | | 2005 |
| CLM Lettings Limited | Real estate | 2006 |
| CMP Products Limited | Manufacturing | 2007 |
| Cock & Bull Amble Ltd | Hospitality | 2024 |
| Coffee Johnny's Limited | Wholesale & retail | 2006 |
| Coles Consultants Ltd | Information & communication | 2003 |
| Colin Lilley Estate Agents Limited | Real estate | 2004 |
| Collingwood Court Management Company Limited | Real estate | 1990 |
| Collingwood Mansions Residents Management Company Limited | Households | 2005 |
| Commissioners Wharf Maintenance Limited | Households | 1999 |
| Community Help and Neighbourly Care for Everyone | Other services | 1998 |
| Computer Orbit Limited | Wholesale & retail | 1981 |
| Concept Informatics Limited | Information & communication | 1999 |
| Connor Group Limited | Financial services | 1999 |
| Connor Solutions Limited | Manufacturing | 1999 |
| Coolcheck Limited | Financial services | 2019 |
| Coravid Solutions Limited | Information & communication | 2007 |
| Coriander Restaurant (Sunderland) Limited | Hospitality | 2005 |
| Cowper Shaw (Security Services) Limited | Manufacturing | 1994 |
| Coyless Limited | Wholesale & retail | 2026 |
| Coyne Interiors Ltd | Construction | 2004 |
| Creative Management Services Limited | Hospitality | 2001 |
| CSM Architects LLP | | 2007 |
| Curious Accommodation Ltd | Hospitality | 2024 |
| Cusdec Ltd | Administrative & support | 2016 |
| CWP Properties Limited | Construction | 2003 |
| D & H Associates (North East) Limited | Arts & recreation | 2001 |
| D and C Dent Removal Limited | Professional & scientific | 2003 |
| D Bland Plumbing & Heating Ltd | Construction | 2017 |
| D J M S Solicitors Ltd | Professional & scientific | 2006 |
| D Lincoln Limited | Construction | 2002 |
| D Macfarlane & SON Limited | Wholesale & retail | 2008 |
| D.A. Cummings Limited | Transport & logistics | 1997 |
| D.G. Todd Limited | Construction | 2004 |
| D.I.T. Motorcycle Repairs Ltd | Wholesale & retail | 1999 |
| Dance North | Arts & recreation | 1990 |
| Dancorr Limited | Transport & logistics | 1994 |
| Danril Engineering Services Limited | Professional & scientific | 2020 |
| Dart Plumbing Heating Electrical Ltd | Construction | 2002 |
| Decke (Newcastle) Limited | Construction | 2000 |
| Decorcare Northeast Ltd | Construction | 2007 |
| Decoy Creative Limited | Professional & scientific | 2004 |
| Delair Investments Limited | Professional & scientific | 2006 |
| Denmark Street Dental Practice Limited | Health & social care | 2007 |
| Dental Studio Prosthetics Limited | Health & social care | 2004 |
| Dependable Bodies (Newcastle) Limited | Manufacturing | 1966 |
| Derliz Limited | Health & social care | 2003 |
| Desmond Mcauliffe Hairdressing Limited | Other services | 2003 |
| DEW Properties Limited | Professional & scientific | 2000 |
| Dhaliwal News Limited | Wholesale & retail | 2005 |
| Dillhaven Limited | Real estate | 1976 |
| Direct 4 U Ltd | Wholesale & retail | 2003 |
| DMC Electrical Services (North East) Limited | Manufacturing | 2002 |
| DMT Environmental Technology UK Limited | Manufacturing | 2024 |
| DMU Solutions Limited | Transport & logistics | 2007 |
| DO U Want 2 Limited | Information & communication | 2005 |
| Dodds Associates Limited | Professional & scientific | 2002 |
| Dodgy Clutch Staged Presentations Limited | Arts & recreation | 2000 |
| Dolphin Quays (North Shields) Limited | Households | 1991 |
| Dong JIN Precision U.K. Limited | Manufacturing | 1995 |
| Dowse Crane Hire Limited | Administrative & support | 2003 |
| Drawroof Limited | Energy | 1972 |
| Druid IB Limited | Administrative & support | 2005 |
| Dryden Furniture (Manufacturing) Ltd | Water & waste | 1995 |
| Dulai Deep Blue Ltd | Hospitality | 2012 |
| Dunbar Plastering Company Ltd | Construction | 2004 |
| Dunn & Co. (Shopfitters) Limited | Arts & recreation | 1977 |
| Durham Benevolence Limited | Extraterritorial | 1956 |