| Calm Network Ltd | Professional & scientific | 2016 |
| Calug First Ltd | Transport & logistics | 2025 |
| CAM Family Meats Limited | Wholesale & retail | 2020 |
| Cam-Era Utilities Ltd | Administrative & support | 2025 |
| Cambridge Court Developments Limited | Wholesale & retail | 2004 |
| Camden House (Darlington) Limited | Real estate | 2017 |
| Camel Safety Solutions Ltd | Professional & scientific | 2025 |
| Cameron Books (Production) Limited | Information & communication | 1981 |
| Cameron Dade Ltd | Information & communication | 2023 |
| Cameron Pearson Ltd | Administrative & support | 2025 |
| CAN Commercial Ltd | Wholesale & retail | 2023 |
| Canbar Maintenance Ltd | Hospitality | 2024 |
| Candiva Enterprises Limited | Other services | 2019 |
| Caneri Ltd | Manufacturing | 2025 |
| Canine Creations (Darlington) Limited | Other services | 2015 |
| Cannbridge Catering Ltd | Hospitality | 2016 |
| Cannie Investments Limited | Financial services | 2020 |
| Cannie Properties Ltd | Real estate | 2021 |
| Canuto Ltd | Hospitality | 2026 |
| Canwar Pavilion Ltd | Hospitality | 2024 |
| Canwar Sportsman Ltd | Hospitality | 2024 |
| Capability James Limited | Administrative & support | 2008 |
| Cappuccemo Coffee Co. Limited | Hospitality | 2025 |
| Car Monster Limited | Administrative & support | 1996 |
| Car Storage Yorkshire Limited | Transport & logistics | 2023 |
| Cardiff Money Limited | Financial services | 2019 |
| Cardiovision Ltd | Health & social care | 2022 |
| Cardshark (NE) Limited | Wholesale & retail | 2019 |
| Cardshark (North East) Limited | Wholesale & retail | 2019 |
| Cardshark (Northern) Limited | Wholesale & retail | 2019 |
| Cardshark (UK) Limited | Wholesale & retail | 2019 |
| Cardshark Durham Limited | Wholesale & retail | 2019 |
| Care Matters (Homecare) Limited | Health & social care | 2013 |
| Care Matters (Middlesbrough) Limited | Health & social care | 2019 |
| Care Matters (North Yorkshire) Limited | Health & social care | 2025 |
| Care Taylormade Ltd | Health & social care | 2015 |
| Carelink Staffing Solutions Limited | Health & social care | 2025 |
| Carevantage Ltd | Health & social care | 2020 |
| Cargo Pallets (Teesside) Ltd | Manufacturing | 2024 |
| Caring Gentle Dental Centre Limited | Health & social care | 2008 |
| Carlaw Property Group Ltd | Real estate | 2025 |
| Carlo City Limited | Wholesale & retail | 2026 |
| Carmel Structures Limited | Construction | 2000 |
| Carnaby Sales Limited | Wholesale & retail | 2015 |
| Carol Lancaster Limited | Health & social care | 2022 |
| Carousel Catering NE Ltd | Hospitality | 2024 |
| Carousel Confectioners Ltd | Hospitality | 2024 |
| Carpet Guru Limited | Wholesale & retail | 2018 |
| Carpet Ninja Ltd | Administrative & support | 2025 |
| Carrs Fine Art and Furniture Carrier Ltd | Transport & logistics | 2017 |
| Carruthers and Jackson Limited | Professional & scientific | 2018 |
| CARS25 Limited | Wholesale & retail | 2025 |
| Carter Dixon Mcgill Ltd | Arts & recreation | 2022 |
| Carter Thompson & Associates Limited | Financial services | 2014 |
| Carterr Limited | Wholesale & retail | 2026 |
| Cartronix Ltd | Professional & scientific | 2013 |
| Carver Lettings Limited | Real estate | 2015 |
| Caspica Trading Limited | Information & communication | 2018 |
| Cass Investment Co Ltd | Real estate | 2018 |
| Cassabian Limited | Hospitality | 2015 |
| Cassore Ltd | Wholesale & retail | 2025 |
| Cast & Catch Angling Centre Ltd | Wholesale & retail | 2026 |
| Castle Bridge Consulting (Investments) Limited | Real estate | 2023 |
| Castle Bridge Consulting Limited | Professional & scientific | 2023 |
| Castle Homes Maintenance Ltd | Construction | 2024 |
| Castle Homes Property Ltd | Real estate | 2019 |
| Castle Investments NE Ltd | Real estate | 2025 |
| Castleton Station Limited | Real estate | 2024 |
| Catcastle Property Company Limited | Real estate | 2017 |
| Catcastle Quarry Ltd | Real estate | 2025 |
| Cater Solutions Limited | Wholesale & retail | 2025 |
| Cath Christie @ Dermasmooth Ltd | Other services | 2016 |
| Cathedral Shutters and Blinds Ltd | Manufacturing | 2014 |
| Catterick Property Services Ltd | Construction | 2025 |
| Caught in the Web Limited | Information & communication | 2011 |
| Cause for Change Ltd | Professional & scientific | 2014 |
| Cayman Holdings Limited | Wholesale & retail | 2022 |
| Cazzyclad Limited | Construction | 2018 |
| CB Access Ltd | Construction | 2023 |
| CBT British Psychotherapy Limited | Health & social care | 2018 |
| CC Creative Design Ltd | Professional & scientific | 2021 |
| CC Marketing Ltd | Professional & scientific | 2022 |
| CC OM Subco Limited | Health & social care | 2026 |
| Ccvl Ltd | Transport & logistics | 2023 |
| CD Dog Training Ltd | Other services | 2024 |
| CD Elliott Limited | Wholesale & retail | 2024 |
| CD Simpson Consultancy Ltd | Professional & scientific | 2012 |
| CDF Leisure Ltd | Hospitality | 2018 |
| CDM (NE) Ltd | Construction | 2008 |
| CDS Logistics Limited | Transport & logistics | 2021 |
| CDS Property and Developments Ltd | Real estate | 2024 |
| Celdec Ltd | Construction | 2021 |
| Cellnex (NE) Ltd | Wholesale & retail | 2023 |
| Cennan Ltd | Administrative & support | 2025 |
| Centaur Systems Ltd | Information & communication | 2004 |
| Centre Barks Limited | Agriculture & fishing | 2022 |
| Centre Stagers Limited | Wholesale & retail | 2025 |
| Cerberus Enterprises Ltd | Other services | 2015 |
| Certus Property Services Limited | Administrative & support | 2013 |
| CF Engineering Services Ltd | Professional & scientific | 2026 |