| C T Welding Inspection Limited | Construction | 2015 |
| C&G Accounting Ltd | Real estate | 2020 |
| C&S Gilding Limited | Hospitality | 2024 |
| C&V Property Services Ltd | Real estate | 2018 |
| C. LEE Limited | Professional & scientific | 2003 |
| C.A.M. Services Limited | Professional & scientific | 2007 |
| Cafe Istanbul (Redcar) Limited | Hospitality | 2023 |
| CAG Housing Limited | Real estate | 2020 |
| Caldan Conveyor Limited | Manufacturing | 2015 |
| Campfire Fitness Ltd | Arts & recreation | 2021 |
| Canalside and Waterside Lofts Management Ltd | Households | 2023 |
| Canisapien Ltd | Manufacturing | 2023 |
| Canterbury Media and Events Limited | Administrative & support | 2022 |
| Car Care of Marske Limited | Wholesale & retail | 2003 |
| Caremore Services Limited | Health & social care | 2006 |
| Carers Together Foundation | Information & communication | 2008 |
| Carl J Potts Ltd | Professional & scientific | 2017 |
| Cartwright Carpets Limited | Wholesale & retail | 2014 |
| Cassagh Automation Limited | Professional & scientific | 2023 |
| Castle Productions Films Ltd | Information & communication | 2016 |
| CCT Electrical Ltd | Construction | 2024 |
| Centre for Process Innovation Limited | Professional & scientific | 2003 |
| Cerus Solutions Ltd | Information & communication | 2017 |
| Cessford Holdings Ltd | Financial services | 2023 |
| Cgab Limited | Transport & logistics | 2020 |
| CH Couriers Ltd | Transport & logistics | 2026 |
| Chans Redcar Ltd | Hospitality | 2026 |
| Charlie Parkes Ltd | Real estate | 2023 |
| Charm Theatrical Productions UK Limited | Arts & recreation | 2019 |
| Children's Rooms Limited | Wholesale & retail | 2005 |
| Chris Horne EPC Ltd | Professional & scientific | 2019 |
| Chris Horne Holdings Ltd | Financial services | 2024 |
| Chris Horne Retrofit Ltd | Administrative & support | 2021 |
| Christian Mark David Cawley Limited | Information & communication | 2016 |
| Christopher Cooper Logistics Ltd | Transport & logistics | 2025 |
| Cinkivitch Ltd | Manufacturing | 2024 |
| CJJ Solutions Limited | Professional & scientific | 2016 |
| Clarendon Property Ltd | Real estate | 2020 |
| Clare’S Care Ltd | Health & social care | 2023 |
| Claxton Consultant Limited | Professional & scientific | 2007 |
| Clay Drilling Limited | Construction | 2016 |
| Claybury Limited | Construction | 2004 |
| Clevechem Limited | Wholesale & retail | 1974 |
| Cleveland Circuits Limited | Manufacturing | 1971 |
| Cleveland Circuits (Skelton) Limited | Professional & scientific | 1993 |
| Cleveland Damp Solutions Ltd | Construction | 2025 |
| Cleveland Technologies Limited | Manufacturing | 2008 |
| Cleveland Technologies Trustees Limited | Administrative & support | 2021 |
| Cleveland Women's Network CIC | Administrative & support | 2019 |
| Climatec Engineering Limited | Manufacturing | 2017 |
| CLM Coatings Limited | Manufacturing | 2025 |
| Clmp Properties Limited | Real estate | 2023 |
| Clnm Properties Ltd | Real estate | 2021 |
| CMK Engineering Ltd | Professional & scientific | 2025 |
| CMS Logistics Limited | Transport & logistics | 2016 |
| Coastal Campers Ltd | Wholesale & retail | 2017 |
| Coastal Draughting Ltd | Professional & scientific | 2019 |
| Coastal Kitchens, Bedrooms and Bathrooms Ltd | Manufacturing | 2025 |
| Coatham Arena Limited | Construction | 2021 |
| Coatham House | Hospitality | 1993 |
| Coatham House Enterprises Limited | Hospitality | 2010 |
| Coffee, Cake & Chlo Ltd | Hospitality | 2025 |
| Cogs North East Limited | Health & social care | 2019 |
| Collins Dale Enterprises Ltd | Wholesale & retail | 2011 |
| Collins Inspection Limited | Professional & scientific | 2009 |
| Community Stepping Stones CIC | Hospitality | 2018 |
| Company First CIC | Health & social care | 2019 |
| Concept Cubicles Limited | Construction | 2014 |
| Conflict Management Training Ltd | Administrative & support | 2006 |
| CONNECT-2 Technology Limited | Professional & scientific | 1995 |
| Connor Blakey Logistics Limited | Transport & logistics | 2025 |
| Coopers Chemist Gt.Ayton Limited | Wholesale & retail | 1978 |
| Coopers Chemist Marske Limited | Wholesale & retail | 1977 |
| Coopers Chemist Redcar Limited | Wholesale & retail | 1985 |
| Copious Rope Access Services Ltd | Construction | 2020 |
| Cora Childcare Estates Ltd | Real estate | 2026 |
| Cora Childcare Holdings Ltd | Financial services | 2026 |
| Cora Childcare Ltd | Health & social care | 2024 |
| Corner Property Investments Ltd | Real estate | 2023 |
| Costech Homes Limited | Construction | 2024 |
| Cosy Clean Limited | Administrative & support | 2026 |
| Counsellingwithlouise Ltd | Other services | 2025 |
| Cove Medical Clinic Ltd | Health & social care | 2026 |
| Cozy Calm Limited | Manufacturing | 2024 |
| CPI Enterprises Limited | Professional & scientific | 2009 |
| CPI Innovation Services Limited | Professional & scientific | 2006 |
| CPI Innovation Services Trust Limited | Financial services | 2008 |
| CPI Vaccines Limited | Extraterritorial | 2008 |
| CPL Motors Ltd | Wholesale & retail | 2018 |
| Cpnd Ltd | Real estate | 2021 |
| Cpnd Properties LLP | | 2021 |
| Cpsp LLP | | 2021 |
| Cpsp Properties Ltd | Real estate | 2021 |
| Cragglenett Solutions Ltd | Information & communication | 2025 |
| Craggs Property Investments Ltd | Real estate | 2019 |
| Craig Moore Plumbing & Heating Ltd | Construction | 2018 |
| Creative Driveways (NE) Limited | Construction | 2018 |
| Crestfix Limited | Real estate | 2002 |
| CRN Project Planning Ltd | Professional & scientific | 2017 |
| Crown Comps Limited | Wholesale & retail | 2024 |