| Collingwood Solutions Limited | Professional & scientific | 2018 |
| Collingwood Terrace Limited | Real estate | 2022 |
| Collins Bros Ltd | Construction | 2020 |
| Collinsdale Limited | Financial services | 1992 |
| Colorlites Holdings Limited | Financial services | 2018 |
| Colorpeak Ltd | Professional & scientific | 2016 |
| Coloured Bottles Limited | Wholesale & retail | 1984 |
| Coloured Hearts C.I.C. | Education | 2025 |
| Coltech Design Services Ltd | Professional & scientific | 2026 |
| Comarketing (UK) Limited | Professional & scientific | 2001 |
| Combined Arms Limited | Real estate | 2010 |
| Combo Properties Limited | Real estate | 2021 |
| Combo Services Limited | Real estate | 2016 |
| Come View My Art Gallery Limited | Administrative & support | 2023 |
| Comfort Cooling Solutions (North East) Ltd | Construction | 2018 |
| Commercial & Temperance Developments LLP | | 2010 |
| Commercial Maintenance Services UK Limited | Administrative & support | 2000 |
| Commercial Tyres OFF Highway Limited | Extraterritorial | 2013 |
| Commissioners Wharf RTM Company Limited | Households | 2011 |
| Commodious LLP | | 2012 |
| Community Based Care Bureau Limited | Health & social care | 2016 |
| Community Based Care Health Federation Limited | Health & social care | 1994 |
| Community Based Care Trading Limited | Health & social care | 2020 |
| Community Based Care Workforce Solutions Limited | Health & social care | 2022 |
| Community Funding Network Limited | Professional & scientific | 2026 |
| Compactypist Limited | Information & communication | 1996 |
| Compare Student Rooms Limited | Professional & scientific | 2018 |
| Compare the Energy Market Limited | Administrative & support | 2026 |
| Compare the Supermarket.Ai Limited | Administrative & support | 2026 |
| Compare the Utility Market Limited | Administrative & support | 2016 |
| Complete Clinics Limited | Other services | 2025 |
| Complete Community Home Care Limited | Health & social care | 2018 |
| Complete Construction NE Limited | Construction | 2021 |
| Complete Construction Northern Limited | Construction | 2021 |
| Complete Conversions (N.E.) Limited | Construction | 2020 |
| Complete Energy (NE) Limited | Administrative & support | 2023 |
| Complete Property Services (N.E.) Limited | Construction | 2022 |
| Computer Geeks Ltd | Information & communication | 2008 |
| Computers R US Ltd | Wholesale & retail | 2021 |
| Computronix Limited | Wholesale & retail | 2023 |
| Comunico Limited | Information & communication | 2013 |
| Concept Architecture Ltd | Professional & scientific | 2010 |
| Concept Care Practice Limited | Administrative & support | 1996 |
| Conceptbalance Limited | Professional & scientific | 1997 |
| Concrete Force Limited | Construction | 2020 |
| Connectment Limited | Administrative & support | 2013 |
| Consett Hand Carwash (NE) Ltd | Other services | 2024 |
| Consult Claire Limited | Other services | 2025 |
| Continental Networks Ltd | Construction | 2018 |
| Contract Candles & Diffusers Ltd | Manufacturing | 2004 |
| Contract Candles Limited | Transport & logistics | 1995 |
| Contraxus Limited | Information & communication | 2026 |
| Convey Bros Ltd | Other services | 2025 |
| Cookes & Peggs Limited | Information & communication | 2009 |
| Cookham House (Dunston Riverside) Management Limited | Households | 2002 |
| COOKING4LIFE Limited | Education | 2009 |
| Cool Designs Holdings Limited | Energy | 2012 |
| Cool Designs Limited | Manufacturing | 2002 |
| Cool Kegs Cellar Cooling Limited | Extraterritorial | 2023 |
| Cool Planet Group (UK) Limited | Information & communication | 2021 |
| Coombes Transport Limited | Transport & logistics | 2026 |
| Cooperized Dyno and Service Centre Limited | Wholesale & retail | 2012 |
| Copper Blue Creative Limited | Professional & scientific | 2012 |
| Copper Tree Furniture Ltd | Manufacturing | 2021 |
| Copro Consulting Limited | Professional & scientific | 2008 |
| Coquet Cycles Limited | Wholesale & retail | 2011 |
| Coquet Trust | Health & social care | 2007 |
| COR Advisory Limited | Administrative & support | 2020 |
| COR Business Services (Northern) Limited | Other services | 2011 |
| Corbridge Coffee Ltd | Hospitality | 2025 |
| Core Assets (Gateshead) Ltd | Financial services | 2023 |
| Core Catering Maintenance Contracts Limited | Construction | 2013 |
| Core Catering Maintenance Limited | Manufacturing | 2013 |
| Corelith Labs Ltd | Information & communication | 2025 |
| Cornerstone Capital & Property Ltd | Real estate | 2025 |
| Cornerstone Financial Group Limited | Financial services | 2020 |
| Cornerstones Property Investments Ltd | Real estate | 2025 |
| Cornick and Morris Limited | Manufacturing | 2002 |
| Cornlab Innovations Ltd | Manufacturing | 2021 |
| Corona Services (NE) Limited | Construction | 2018 |
| Corrines Care Limited | Public administration | 2025 |
| Coshabang Ltd | Administrative & support | 2020 |
| Cosmetic Contours Asthetics Limited | Administrative & support | 2017 |
| Cosmetic Paint Systems (North East) Limited | Wholesale & retail | 2003 |
| Cosmo Grace Limited | Real estate | 2022 |
| Cosmo Grace Property Ltd | Real estate | 2017 |
| Cosmo Planet Properties Ltd | Real estate | 2025 |
| Costcutter (Dunston) Ltd | Wholesale & retail | 2017 |
| Costello Northeast Ltd | Information & communication | 2013 |
| Cosy Homes Property Development and Rentals Ltd | Other services | 2018 |
| Cosy Living Limited | Hospitality | 2017 |
| Cotana Collection Limited | Wholesale & retail | 2023 |
| Cotemede Convenience Ltd | Wholesale & retail | 2026 |
| Cotemede Leisure Limited | Hospitality | 2024 |
| Cotswolds Hospitality Ltd | Hospitality | 2015 |
| Country and County Property Investments Ltd | Real estate | 2019 |
| COURSE4ALL Limited | Education | 2024 |
| CP & SW Ltd | Real estate | 2019 |
| CP Fibre Optics Ltd | Construction | 2018 |
| CP Flooring North East Ltd | Construction | 2023 |