| Comvex Agri Ltd | Wholesale & retail | 2024 |
| Comvex Exports Ltd | Wholesale & retail | 2015 |
| Comvex Plant & Machinery Ltd | Wholesale & retail | 2015 |
| Comvex Trading Ltd | Wholesale & retail | 2007 |
| Conkemp Innovations LLP | | 2009 |
| Conleys Catering Limited | Hospitality | 2025 |
| Conlons (Furnished Lettings) Limited | Hospitality | 2004 |
| Conlons Lodge Limited | Hospitality | 2004 |
| Connected Concepts Limited | Information & communication | 2008 |
| Connected IT Solutions Ltd | Information & communication | 2013 |
| Connor Family Lettings Limited | Real estate | 2026 |
| Consignia Logistics Ltd | Transport & logistics | 2020 |
| Consortium of Voluntary Adoption Agencies UK Limited | Other services | 2004 |
| Construction Training Company Ltd | Education | 2016 |
| CONSTRUCTIONC3 Ltd | Professional & scientific | 2021 |
| Consulting 2018 Limited | Wholesale & retail | 2018 |
| Consultus (Building Consultants) Limited | Construction | 1976 |
| Consultus Developments Limited | Real estate | 2007 |
| Container Sales & Hire Ltd | Wholesale & retail | 2016 |
| Container Sales (UK) Limited | Wholesale & retail | 1992 |
| Contemporary Roofline Limited | Construction | 2011 |
| Control Flow Technologies Group Limited | Administrative & support | 2025 |
| Control Flow Technologies Limited | Extraterritorial | 2020 |
| Control Flow Training Academy Ltd | Education | 2026 |
| Cooke on GAS Ltd | Construction | 2022 |
| Cookie Freaks Ltd | Manufacturing | 2019 |
| Cooklaw Solicitors Ltd | Professional & scientific | 2017 |
| Cooks Estates Ltd | Real estate | 2026 |
| Cool Guys Ltd | Hospitality | 2024 |
| Cooper-Shirt Ltd | Financial services | 2021 |
| Copeland Capital Ltd | Construction | 2023 |
| Corby Hall Sunderland (Management) Limited | Households | 1978 |
| Core Wealth Management (NE) Limited | Administrative & support | 2015 |
| CORE3 Vitality Ltd | Manufacturing | 2023 |
| Corner 93 Ltd | Wholesale & retail | 2024 |
| Cornerstone Consulting Solutions (UK) Limited | Information & communication | 2009 |
| Cornerstone Safety Limited | Public administration | 2025 |
| Corpsustain Ventures UK Limited | Professional & scientific | 2025 |
| Corso Hospitality Ltd | Hospitality | 2026 |
| Cosc Supplies Limited | Administrative & support | 1997 |
| Cosmos Creations Ltd | Information & communication | 2025 |
| Costcutters (West Rainton) Limited | Wholesale & retail | 2009 |
| Cosy Home Solutions Limited | Construction | 2018 |
| Cosy Home Solutions UK Limited | Construction | 2018 |
| Cosyfit Flooring Ltd | Construction | 2022 |
| Cosylets North East Limited | Real estate | 2024 |
| Cottin Leisure Limited | Hospitality | 2014 |
| Cotton Fresh Cleaners Ltd | Administrative & support | 2020 |
| Coulson Luxury Safes Limited | Administrative & support | 2015 |
| Couriers of the North East Ltd | Transport & logistics | 2025 |
| Couriers of the North Ltd | Transport & logistics | 2025 |
| Cousins Building and Roofing Services Limited | Construction | 2005 |
| Cove Salon Ltd | Other services | 2024 |
| Covert Surveillance Ltd | Administrative & support | 2019 |
| Cowper Shaw & Company Limited | Professional & scientific | 1967 |
| COX Construction NE Ltd | Construction | 2023 |
| Coxgreen Old School House Kitchen Ltd | Hospitality | 2022 |
| Coxhoe Pizza Ltd | Hospitality | 2024 |
| Coxon OIL and GAS Ltd | Construction | 2015 |
| CP Property and Lettings Limited | Real estate | 2017 |
| CPG1 Ltd | Professional & scientific | 2023 |
| CPM (NE) Engineering Limited | Manufacturing | 2004 |
| Cpsr PMC Ltd | Other services | 2018 |
| CR Commercial & Domestic Cleaning Ltd | Administrative & support | 2026 |
| CR Fitness Franchise Ltd | Arts & recreation | 2019 |
| CR Wind Services Ltd | Manufacturing | 2025 |
| Crabhadail Trading Limited | Financial services | 2025 |
| Crabtree & Blacklock Bespoke Interiors Limited | Construction | 2021 |
| Cracked POT Enterprises CIC | Manufacturing | 2021 |
| Craic and Connect Games Ltd | Manufacturing | 2026 |
| Craig Mcgarrell Limited | Professional & scientific | 2018 |
| Cram Media UK Ltd | Information & communication | 2026 |
| Crawford Knox Limited | Information & communication | 2025 |
| Crazy Candy Floss Ltd | Wholesale & retail | 2024 |
| Crazy Carpets Weekly Ltd | Wholesale & retail | 2018 |
| Crazy Chops Bistro Limited | Hospitality | 2025 |
| Crazy Mist Limited | Real estate | 2009 |
| CRC Leisure Ltd | Hospitality | 2019 |
| CRE Rail Ltd | Construction | 2014 |
| Creating Sunshine CIC | Manufacturing | 2023 |
| Creative Inclusion Consultancy Ltd | Health & social care | 2022 |
| Creditable Resources Limited | Professional & scientific | 2014 |
| Creo Communications Limited | Professional & scientific | 2014 |
| Crescent Moon Developments Limited | Real estate | 2026 |
| Crest Safe & Vault Limited | Administrative & support | 2009 |
| Crew Corner Limited | Other services | 2016 |
| Crinson Holdings Ltd | Financial services | 2023 |
| Crisofa Group Ltd | Health & social care | 2022 |
| Crisp N FRY Ltd | Hospitality | 2018 |
| Cristem Limited | Hospitality | 2017 |
| CRM PPM Limited | Information & communication | 2023 |
| Crofters Properties Limited | Real estate | 2024 |
| Croo Studio Limited | Professional & scientific | 2023 |
| Crosby Property Management Ltd | Real estate | 2019 |
| Crossed Arms Limited | Information & communication | 2025 |
| Crown and Pearls International Ltd | Wholesale & retail | 2020 |
| Crownandtrowel Ltd | Construction | 2026 |
| Crowns & Gowns Ltd | Health & social care | 2025 |
| Crowther Mediation Limited | Other services | 2017 |
| CRS Cornerstone Limited | Administrative & support | 2015 |