| C I Accountancy (UK) Limited | Extraterritorial | 2016 |
| C J LEE Consulting Engineers Ltd | Professional & scientific | 2025 |
| C T Haulage Ltd | Transport & logistics | 2016 |
| C-Level Impact Ltd | Professional & scientific | 2025 |
| C. P. H. Training Limited | Construction | 2016 |
| C. S. Transport Consultancy Limited | Professional & scientific | 2022 |
| C.I. Accountancy Limited | Professional & scientific | 2002 |
| Cafe Enna Limited | Hospitality | 2011 |
| Café @ Burn Lane Limited | Hospitality | 2018 |
| Cal's Braai Box Ltd | Hospitality | 2023 |
| Caledonia Golf Ltd | Administrative & support | 2024 |
| Calorem Ltd | Professional & scientific | 2018 |
| Calvin's Cuisine Ltd | Hospitality | 2018 |
| Campact Limited | Manufacturing | 1988 |
| Candytuft Design Limited | Manufacturing | 2022 |
| Canny Canines DC Limited | Other services | 2024 |
| Cape Pharma Insights Ltd | Professional & scientific | 2025 |
| Capeacre Limited | Real estate | 1981 |
| Carbon Negative Ltd | Professional & scientific | 2011 |
| Carmichael Farming | Administrative & support | 2012 |
| Caroline Murphy Psychological Services Ltd | Health & social care | 2023 |
| Carriages Tearoom (Bellingham) Ltd | Hospitality | 2017 |
| Casanova Ltd | Hospitality | 2012 |
| Castanean (Holdings) Ltd | Financial services | 2020 |
| Castle IT Systems Limited | Information & communication | 2014 |
| Castle of Cards Ltd | Wholesale & retail | 2022 |
| Cat in the Barrow Enterprises Ltd | Information & communication | 2025 |
| Catholic Voices | Education | 2011 |
| Catwalking Limited | Extraterritorial | 2000 |
| Causey Way Solutions Ltd | Information & communication | 2024 |
| CB Hearing and Balance Ltd | Health & social care | 2021 |
| CCS Logistics (Europe) Limited | Administrative & support | 2015 |
| CD Johnson Limited | Construction | 2012 |
| Cedar Computers Limited | Information & communication | 1983 |
| Cellopath Ltd | Health & social care | 2017 |
| Centurion Computers Ltd | Other services | 2016 |
| Ceres Energy Limited | Energy | 2008 |
| Ceres Energy Solutions Limited | Energy | 2020 |
| Ceres Energy Trustee Limited | Financial services | 2025 |
| CES (Civil Engineering Solutions) Limited | Professional & scientific | 2022 |
| CG Property Partners Ltd | Real estate | 2025 |
| CHA Newco Limited | Financial services | 2019 |
| Champion Drinks Ltd | Wholesale & retail | 2024 |
| Chapel Retreats Ltd | Hospitality | 2024 |
| Charles Murphy Wines Ltd | Wholesale & retail | 2020 |
| Charlotte Gaisford Ltd | Manufacturing | 2014 |
| Charlton Drainage Limited | Construction | 2007 |
| Cheese Scone Ltd | Hospitality | 2019 |
| Cheviot Watches Ltd | Manufacturing | 2025 |
| Chintah Ltd | Hospitality | 2019 |
| Chipchase Farms Limited | Agriculture & fishing | 2011 |
| Christopher Moore Limited | Professional & scientific | 1964 |
| CIS (North East) Ltd | Administrative & support | 2014 |
| Cityview Limited | Construction | 1984 |
| Civikas Limited | Professional & scientific | 2019 |
| CJ Logistics (NE) Ltd | Transport & logistics | 2023 |
| CK Pearson Properties Ltd | Real estate | 2019 |
| Clanmade Limited | Information & communication | 2020 |
| Clarand Accountants Limited | Professional & scientific | 2012 |
| Clark-Agile Ltd. | Wholesale & retail | 2017 |
| Clean Energy Advisory Ltd | Professional & scientific | 2023 |
| Clean Pristine Limited | Administrative & support | 2020 |
| Clean Waste Services Ltd | Water & waste | 2018 |
| Cliddle Consulting Ltd | Professional & scientific | 2019 |
| Close Healthcare UK Ltd | Health & social care | 2014 |
| Cloudsale Consulting Limited | Professional & scientific | 2023 |
| Cmkcorporate Ltd | Wholesale & retail | 2009 |
| Codlaw Renewable Energy Limited | Energy | 2013 |
| Coleman Mulligan Ltd | Hospitality | 2016 |
| Colin White Tree Surgery Limited | Agriculture & fishing | 2015 |
| Collingwood Electrotechnical Services Limited | Construction | 2020 |
| Collingwood Street Limited | Real estate | 2018 |
| Colliscope Ltd | Professional & scientific | 2025 |
| Collision Repair Group Limited | Wholesale & retail | 2017 |
| Colpitts Grange Residents Association Ltd | Households | 1992 |
| Community Archaeology North CIC | Professional & scientific | 2024 |
| Compass Pipelines Limited | Professional & scientific | 1998 |
| Congruity Limited | Information & communication | 2015 |
| Consett Aggregates Limited | Wholesale & retail | 2026 |
| Construction Management Consultants (U.K.) Limited | Administrative & support | 1991 |
| Contract Guru Limited | Professional & scientific | 2015 |
| Cooper Wood Limited | Agriculture & fishing | 2025 |
| Corbridge Optical Ltd | Health & social care | 2022 |
| Core Music Community Interest Company | Arts & recreation | 2007 |
| Cork Tree Ltd | Wholesale & retail | 2005 |
| Corsenbio Consulting Ltd | Professional & scientific | 2023 |
| Cosmic Frequencies Events CIC | Education | 2026 |
| Cosy Rentals Ltd | Real estate | 2016 |
| CPD Actif Ltd | Professional & scientific | 2012 |
| Cpfg Europe Ltd | Other services | 2020 |
| Creating Classrooms Limited | Education | 2019 |
| Creating Games Ltd | Professional & scientific | 2018 |
| Creation ID Limited | Administrative & support | 2005 |
| Credere Media Ltd | Professional & scientific | 2016 |
| Crosland Consulting Limited | Professional & scientific | 2014 |
| Crow.Fse Ltd | Professional & scientific | 2020 |
| CSD Homes North East Ltd | Information & communication | 2024 |
| CSV Compliance Limited | Information & communication | 2014 |
| CT Performance Limited | Health & social care | 2022 |
| CTT Northumberland Ltd | Transport & logistics | 2025 |