| Candy Castle Animation Ltd | Information & communication | 2021 |
| Canisblue Limited | Professional & scientific | 2024 |
| Capital Cleaning North East Ltd | Administrative & support | 2021 |
| Capital Edge Property Solutions Ltd | Construction | 2025 |
| Capitar Enterprise Limited | Extraterritorial | 2013 |
| Capo Properties Ltd | Real estate | 2025 |
| Capsy's Cakes & Bakes Limited | Manufacturing | 2024 |
| Captain Torque Ltd | Wholesale & retail | 2025 |
| Captureready Ltd | Information & communication | 2025 |
| Car and Van Sales Middlesbrough Ltd | Wholesale & retail | 2019 |
| Car Choice (Teesside) Limited | Wholesale & retail | 2007 |
| Car Saver Limited | Wholesale & retail | 2026 |
| Car Wash Apollonia Ltd | Administrative & support | 2025 |
| Carbuyerbuddy Ltd | Wholesale & retail | 2018 |
| Cardboard Sword Games Ltd | Information & communication | 2020 |
| Cardboard Sword Limited | Information & communication | 2013 |
| Care at Home (North East) Limited | Public administration | 2025 |
| Care United (NE) Ltd | Health & social care | 2016 |
| Carefit Carpets Ltd | Construction | 2013 |
| Caretenders Ltd | Administrative & support | 2023 |
| Cargill Estates Ltd | Construction | 2024 |
| Cargo Fleet Developments Ltd | Construction | 2026 |
| Cargo Fleet Football Club Ltd | Arts & recreation | 2026 |
| Carl Anthony Ltd | Administrative & support | 2015 |
| Carl Hamm UK Ltd | Wholesale & retail | 1997 |
| Carl Purvis Rail Ltd | Construction | 2018 |
| Carl R Mitchell Limited | Construction | 2021 |
| Carlbury Technical Services Ltd | Administrative & support | 2018 |
| Carless Lifting UK Ltd | Construction | 2026 |
| Carliv Accountancy Limited | Professional & scientific | 2015 |
| Carlton Energy Limited | Construction | 2019 |
| Carlton Energy NO: 1 Limited | Energy | 2024 |
| Carlton Energy NO: 2 Limited | Energy | 2024 |
| Carlton Energy NO: 3 Limited | Energy | 2024 |
| Carlton Energy NO: 4 Limited | Energy | 2024 |
| Carlton Energy NO: 5 Limited | Energy | 2024 |
| Carlton Green Rothwell Limited | Construction | 2014 |
| Carlton Investments (Holdings) Limited | Financial services | 2014 |
| Carlton Nominees Limited | Extraterritorial | 2025 |
| Carlton Power Developments NO: 15 Limited | Manufacturing | 2024 |
| Carlton Power Developments NO: 16 Limited | Manufacturing | 2024 |
| Carlton Power Developments NO: 17 Limited | Energy | 2024 |
| Carlton Power Developments NO: 18 Limited | Manufacturing | 2024 |
| Carlton Power Developments NO: 19 Limited | Manufacturing | 2024 |
| Carlton Power Limited | Construction | 2014 |
| Carlton Power Trading NO. One Limited | Extraterritorial | 2015 |
| Carlton Power Trading NO. Two Limited | Extraterritorial | 2015 |
| Carlton Project Services Ltd | Professional & scientific | 2024 |
| Carman & Forsyth Limited | Professional & scientific | 2018 |
| Carmel Gardens Management Limited | Real estate | 1985 |
| Carnation (NE) Ltd | Wholesale & retail | 2021 |
| Carney Boxing Fitness Limited | Arts & recreation | 2018 |
| Carpet Crafts of Stokesley Ltd | Wholesale & retail | 2012 |
| Carpet DRY Ltd | Other services | 2022 |
| Carrthorpe Limited | Agriculture & fishing | 2023 |
| CARS4LESS Teeside Ltd | Wholesale & retail | 2024 |
| Carter Process Safety Ltd | Professional & scientific | 2026 |
| Cartercom Ltd | Other services | 2017 |
| Carthorse Dolphin Limited | Financial services | 2025 |
| Cartman Access Solutions Ltd | Manufacturing | 2026 |
| Carvid Commercial Project Management Limited | Construction | 1998 |
| Carwebs Motors Limited | Wholesale & retail | 2017 |
| Carzone Motor Finance Ltd | Wholesale & retail | 2024 |
| Casa Romaneasca (NE) Ltd | Wholesale & retail | 2025 |
| Cash in Your Car Limited | Wholesale & retail | 2019 |
| Caskina Limited | Real estate | 2019 |
| Caspara Enterprises Ltd | Manufacturing | 2025 |
| Casper Chartering Limited | Transport & logistics | 2016 |
| Casper Customs Limited | Extraterritorial | 2019 |
| Casper Defence Limited | Transport & logistics | 2002 |
| Casper Port Agency Limited | Extraterritorial | 2016 |
| Casper Shipping Holdings Limited | Financial services | 2014 |
| Casper Shipping Limited | Transport & logistics | 1990 |
| Caspianframe Limited | Real estate | 2023 |
| Cassidy Storytelling Limited | Information & communication | 2017 |
| Casso Sports Ltd | Wholesale & retail | 2025 |
| Castello Interiors Limited | Manufacturing | 2021 |
| Castello Pizzeria Pro Ltd | Hospitality | 2020 |
| Caster Rigging Services Ltd | Construction | 2024 |
| Castle Construction (North East) Limited | Construction | 1997 |
| Castle Court Veterans Village C.I.C. | Hospitality | 2022 |
| Castle Holdings (North East) Limited | Financial services | 2026 |
| Castle Homes North East Limited | Construction | 2005 |
| Castle Racing Co Limited | Hospitality | 2020 |
| Castleton Access Limited | Construction | 2025 |
| Castleton Electrical Ltd | Construction | 2023 |
| Castleworth Investments Ltd | Financial services | 2022 |
| Castleworth Property Development Ltd | Construction | 2022 |
| Cat Access Limited | Professional & scientific | 2013 |
| Catalyst Sports Limited | Wholesale & retail | 2024 |
| Catamountain Limited | Hospitality | 2019 |
| Catenary Services UK Limited | Construction | 2017 |
| Caterpac Supplies Limited | Hospitality | 2025 |
| Catholic Child Welfare Society (Diocese of Middlesbrough) | Other services | 1982 |
| Catterall & Co Ltd | Real estate | 2013 |
| Caveman Construction Company Ltd | Construction | 2018 |
| CAW Consultancy Ltd | Education | 2025 |
| Caynna Store Ltd | Wholesale & retail | 2024 |
| CB Conversions UK Ltd | Extraterritorial | 2021 |
| CB E&I Engineering Solutions Limited | Construction | 2026 |