| Castle and Cathedral Properties Ltd | Real estate | 2025 |
| Castle Eden Catering Limited | Hospitality | 2016 |
| Castle Eden Estates Ltd | Real estate | 2019 |
| Castle Green (Shotton) Management Company Limited | Households | 2013 |
| Castle View Surgery Limited | Health & social care | 2008 |
| Castlebank Development Company Limited | Professional & scientific | 1986 |
| Castlegate Property Solutions Limited | Real estate | 2024 |
| Cataldo Training Ltd | Education | 2025 |
| Cathedral Apartments Management Limited | Real estate | 2012 |
| Cathedral Cleaning Services Ltd | Administrative & support | 2023 |
| Cathedral Hospitality Ltd | Hospitality | 2022 |
| Cathedral Motors Ltd | Wholesale & retail | 2009 |
| Cathedral Press Limited | Information & communication | 2015 |
| Cathedral Property Management Ltd | Households | 2023 |
| Cathedral Rise Property Limited | Real estate | 2026 |
| Cathedral Sports Group Limited | Arts & recreation | 2024 |
| Cathedral Surgical Services Limited | Health & social care | 2022 |
| Cathedral Turf Limited | Extraterritorial | 2005 |
| Cathedrals Court Lane Freehold Limited | Real estate | 2025 |
| Cavalier Trade Ltd | Wholesale & retail | 2025 |
| CB Groundworks NE Ltd | Construction | 2026 |
| CB Machining Solutions Ltd | Manufacturing | 2025 |
| Cbce Group Limited | Financial services | 2025 |
| CBR Refrigeration & Air Conditioning Ltd | Construction | 2023 |
| CC1 Engineering Ltd | Professional & scientific | 2015 |
| CCC Construction Ltd | Construction | 2023 |
| CD ALL Trades Ltd | Construction | 2023 |
| CD Groundworks (NE) Ltd | Construction | 2017 |
| CD Printing Services Limited | Manufacturing | 2026 |
| CD Wines Ltd | Wholesale & retail | 2024 |
| CD96 Limited | Financial services | 2024 |
| CDH Maintenance Limited | Manufacturing | 2023 |
| CDR Furniture Ltd | Construction | 2025 |
| CDS Security & Fire Limited | Financial services | 2009 |
| CDS Security & Fire Services Limited | Administrative & support | 2009 |
| Cedor Limited | Professional & scientific | 2016 |
| Ceen Solar Services Ltd | Construction | 2026 |
| Celtic Cask Company Ltd | Wholesale & retail | 2022 |
| Central and Urban Limited | Construction | 2020 |
| Central and Urban Management Limited | Construction | 2020 |
| Central Culture Development Ltd | Professional & scientific | 2018 |
| Central Durham GP Providers Limited | Health & social care | 2015 |
| Central Utility Services (UK) Limited | Other services | 2012 |
| Centric Healthcare Limited | Health & social care | 2025 |
| Centurion Utilities Ltd | Construction | 2025 |
| Cerebrovia Therapeutics Ltd | Manufacturing | 2025 |
| Certa Cito Light Haulage Ltd | Transport & logistics | 2018 |
| Certa Roofing and Cladding Ltd. | Construction | 2013 |
| Cesstore Ltd | Wholesale & retail | 2025 |
| CF DHM Limited | Arts & recreation | 2023 |
| CF Land (Hanzard Drive) Limited | Real estate | 2020 |
| CF Land Limited | Financial services | 2019 |
| CF Land Residential Limited | Real estate | 2023 |
| CGR Engineering Services Limited | Professional & scientific | 2007 |
| Chain Reaction Entertainment Limited | Hospitality | 2020 |
| Chainbridge Road MOT Ltd | Wholesale & retail | 2025 |
| Chairman Creatives Ltd | Manufacturing | 2025 |
| CHAM3OUN Ltd | Wholesale & retail | 2025 |
| Chameleon Production Studios Limited | Information & communication | 2022 |
| Chameleon Signage Limited | Professional & scientific | 2021 |
| Champagne Cinderella Ltd. | Real estate | 2017 |
| Chancery Capital Partners Limited | Real estate | 2024 |
| Changing Relations C.I.C. | Education | 2013 |
| Chapman & Henderson Construction Limited | Construction | 2015 |
| Chaps Barbers Durham Limited | Other services | 2017 |
| Chapter Engineering Limited | Manufacturing | 2009 |
| Chapter Homes Durham Limited | Construction | 2015 |
| Charles a Newton Ltd | Other services | 2023 |
| Charlies Properties Ltd | Real estate | 2023 |
| Chase Prop Ltd | Households | 2023 |
| Chaska Cafe Ltd | Hospitality | 2026 |
| Chaylak Ltd | Wholesale & retail | 2026 |
| Chefs at Home Ltd | Hospitality | 2024 |
| Cherries Cheers Limited | Wholesale & retail | 2021 |
| Cherry HAS Ltd | Wholesale & retail | 2025 |
| Cherryl Pharoah Consultancy Limited | Health & social care | 2013 |
| Chester LE Geek Ltd | Wholesale & retail | 2024 |
| Chester LE Street Hospitality Company Limited | Hospitality | 2023 |
| Chester-Le-Street CC Trading Limited | Hospitality | 2016 |
| Cheveley Court Management Company Ltd | Households | 2006 |
| Chha (UK) Company Limited | Real estate | 2020 |
| Chic Beauty & Hair Limited | Other services | 2016 |
| Chicco Trade Ltd | Wholesale & retail | 2025 |
| Chicken & Co (NE) Ltd | Hospitality | 2025 |
| Chief Executive Officer Magazine Ltd | Professional & scientific | 2021 |
| Chikiris Ltd | Real estate | 2025 |
| Chill IT Cooling Technologies Ltd | Professional & scientific | 2022 |
| Chkn Limited | Professional & scientific | 2018 |
| Chne Ltd | Real estate | 2012 |
| Chok Chin LEE Limited | Administrative & support | 2011 |
| Chomsu Ltd | Information & communication | 2026 |
| Choppity Ltd | Information & communication | 2021 |
| Chorlex Group Holdings Ltd | Education | 2021 |
| Choudhury Land and Properties Limited | Real estate | 2024 |
| Chris Delivery Service Ltd | Transport & logistics | 2012 |
| Chris Hetherington Flooring Ltd | Wholesale & retail | 2013 |
| Chris Watson Sound Recordings Ltd | Information & communication | 2015 |
| Chriskel Properties Limited | Real estate | 1996 |
| Christ Way Ministries International | Other services | 2023 |
| Christchurch Claypath Durham | Other services | 2004 |