| Continental Shelf 556 Limited | Administrative & support | 2012 |
| Continuous Retort Technologies Limited | Professional & scientific | 2026 |
| Continuous Retorts Limited | Manufacturing | 2019 |
| Contractor IT Services Ltd | Other services | 2021 |
| Control Costs Limited | Professional & scientific | 2023 |
| Control Distributed Trading Branch UK Ltd | Mining & quarrying | 2024 |
| Controlled Bolting Solutions Ltd | Mining & quarrying | 2024 |
| Converged Communications Limited | Information & communication | 2007 |
| Conversations With Purpose Ltd | Administrative & support | 2021 |
| Convertnest Limited | Information & communication | 2026 |
| Cook in a Curry Ltd | Hospitality | 2015 |
| Cook in Style Limited | Health & social care | 2012 |
| Cook Yourself Happier Community Interest Company | Information & communication | 2019 |
| Cookedbyugo Ltd | Hospitality | 2026 |
| Cookiapple Ltd | Arts & recreation | 2025 |
| Cookie Hospitality Ltd | Hospitality | 2015 |
| Cookswell Mews Management Company Limited | Real estate | 2022 |
| Cool Blue Brand Communications Limited | Professional & scientific | 2002 |
| Cool Blue Limited | Extraterritorial | 2017 |
| Cool Britannia A/C Ltd | Construction | 2025 |
| Cool Food Trader Co Limited | Hospitality | 2025 |
| Cool Logic Air Conditioning & Refrigeration Ltd | Construction | 2005 |
| Cool PUB Co Limited | Hospitality | 2016 |
| Coolamber Consulting Limited | Professional & scientific | 2024 |
| Coop Taylor Limited | Real estate | 2010 |
| Cooper Rose Mortgages Limited | Financial services | 2013 |
| Cooper Sowerby Ltd | Real estate | 2024 |
| Copec Tours Ltd | Administrative & support | 2022 |
| Copeland Homes Limited | Extraterritorial | 2004 |
| Copenhagen 1801 Limited | Hospitality | 2011 |
| Copenhagen Logistics Ltd | Transport & logistics | 2020 |
| Copernicus Adriatic LLP | | 2011 |
| Copper Ricebox Ltd | Hospitality | 2023 |
| Copperbelt Electrical Limited | Construction | 2024 |
| Coppercod Ltd | Information & communication | 2020 |
| Copperfield Park (Middleton Tyas) Management Company Limited | Real estate | 2021 |
| Copperfields (Boldon) Management Company Limited | Households | 2007 |
| Coppers@Gosforth Limited | Wholesale & retail | 2013 |
| Coquet Grange (Amble) Management Company Limited | Real estate | 2015 |
| Coquet Hydro Limited | Construction | 2019 |
| Coquet Limited | Real estate | 2023 |
| Coquetdale Apartments Management Company Limited | Real estate | 2007 |
| Cora Health Bidco Ltd | Financial services | 2024 |
| Cora Health Group Ltd | Financial services | 2024 |
| Cora Health Midco Ltd | Financial services | 2020 |
| Cora Health MSK Holdings Ltd | Financial services | 2015 |
| Cora Health MSK Ltd | Health & social care | 1989 |
| Cora Health Pain Services Holdings Ltd | Financial services | 2012 |
| Cora Health Pain Services Ltd | Health & social care | 2006 |
| Corbis Soft Private Limited | Professional & scientific | 2024 |
| Corbitt Stamps Limited | Extraterritorial | 2011 |
| Corbridge Properties Limited | Real estate | 2015 |
| Corbridge Rooms Limited | Hospitality | 2018 |
| Cord Consultants Ltd | Professional & scientific | 2019 |
| Cord Consulting Ltd | Other services | 2023 |
| Cordale Industrial Services Limited | Administrative & support | 2011 |
| Core Data Finance Ltd | Information & communication | 2025 |
| Core International Procurement Limited | Wholesale & retail | 2009 |
| Core Purpose Ltd | Professional & scientific | 2025 |
| Corecare Team Limited | Health & social care | 2021 |
| Coreops Consulting Ltd | Professional & scientific | 2026 |
| Coretin Limited | Wholesale & retail | 2019 |
| Cormeton Electronics Limited | Administrative & support | 2021 |
| Cornel Ventures Limited | Real estate | 2020 |
| Corner House Holdings Ltd | Wholesale & retail | 2022 |
| Corner Shop Chillingham Ltd | Wholesale & retail | 2025 |
| Corner Shop NE4 Ltd | Wholesale & retail | 2022 |
| Corner Shop Newcastle Ltd | Wholesale & retail | 2019 |
| Cornershop Online Limited | Information & communication | 2013 |
| Cornerstone Chemical Company Limited | Manufacturing | 2011 |
| Cornerstone Church Newcastle Limited | Hospitality | 2009 |
| Cornriggs Ltd | Real estate | 2026 |
| Coronet Rail Limited | Manufacturing | 2002 |
| Corp Fitness Group Ltd | Health & social care | 2021 |
| Corporate and Commercial Business Solutions Ltd. | Financial services | 2014 |
| Corporate Care Solutions Limited | Wholesale & retail | 2011 |
| Corporate Cars North East Limited | Extraterritorial | 2018 |
| Corporate Leisure Services (NE) Ltd | Administrative & support | 2019 |
| Correia Mendes Logistics Ltd | Transport & logistics | 2024 |
| Corrigan IT Ltd | Information & communication | 2024 |
| Corrigan Lough Consultants Limited | Professional & scientific | 2015 |
| Corrosion Integrity Management Limited | Professional & scientific | 2018 |
| Corrotech Ltd | Wholesale & retail | 2026 |
| Corter Property Limited | Real estate | 2023 |
| Cortex Surgical Ltd | Wholesale & retail | 2019 |
| Cortijo Coracho Limited | Wholesale & retail | 2026 |
| Corvo-It Ltd | Information & communication | 2025 |
| Cosmic Alva Ltd | Wholesale & retail | 2025 |
| Cosmic Ballroom Limited | Wholesale & retail | 2015 |
| Cosmic Dawn Consulting Ltd | Information & communication | 2019 |
| Cosmic Energy NE Ltd | Wholesale & retail | 2022 |
| Cosmin Prundeanu Logistics Ltd | Transport & logistics | 2025 |
| Cosmopolitan Properties North Ltd | Real estate | 1973 |
| Cosmoss IT Services Ltd | Other services | 2024 |
| Cosplay Collectibles Ltd | Wholesale & retail | 2018 |
| Costa Service Cleaning Ltd | Administrative & support | 2021 |
| Costa Verde Kitchens Ltd | Hospitality | 2025 |
| Costelcalinuk Ltd | Construction | 2025 |
| Costello Ceramics Limited | Construction | 2005 |
| Costello Palmer Communications Limited | Professional & scientific | 2015 |