| Colin Mcginley Funeral Service Ltd | Other services | 2015 |
| Colin's Cards Limited | Wholesale & retail | 2017 |
| Colleum Limited | Manufacturing | 2019 |
| Collier Properties Limited | Real estate | 2002 |
| Collier Property Management LLP | | 2003 |
| Collingdale Ltd | Construction | 2022 |
| Collins Industrial Solutions Ltd | Professional & scientific | 2018 |
| Collins Stirling & Associates Ltd | Administrative & support | 2018 |
| Collinsservgroup Ltd | Construction | 2023 |
| Colthome Developments Limited | Real estate | 2018 |
| Colthome Limited | Construction | 1982 |
| Colthome Properties Limited | Real estate | 2012 |
| COM2CART Ltd | Other services | 2020 |
| Combi (North East) Limited | Manufacturing | 2002 |
| Combined Technical Resource Limited | Administrative & support | 2019 |
| Comfy Homes Limited | Professional & scientific | 1996 |
| Comfy Stayz Limited | Real estate | 2025 |
| Comfy&Cosy UK Ltd | Hospitality | 2024 |
| Command Property Group Limited | Real estate | 2019 |
| Commercial Quarter Ltd | Professional & scientific | 2025 |
| Common Sense Infrastructure Limited | Information & communication | 2025 |
| Communicate Solution (Media) Ltd | Information & communication | 2020 |
| Community Composting C.I.C. | Agriculture & fishing | 2022 |
| Community First Support Network Ltd | Education | 2007 |
| Community Leisure Management Limited | Health & social care | 2016 |
| Community Ventures (Middlesbrough) Ltd. | Professional & scientific | 1989 |
| Community Voice FM Ltd | Information & communication | 2004 |
| Company Appointment Ltd | Professional & scientific | 2015 |
| Company H&H Ltd | Health & social care | 2021 |
| Compare Minibus Travel Ltd | Transport & logistics | 2021 |
| Compassionate Package Ltd | Health & social care | 2021 |
| Competent Mechanical Solutions Ltd | Construction | 2025 |
| Complete Conveyancing (NE) Ltd | Other services | 2020 |
| Complete Digital Services Limited | Information & communication | 2018 |
| Complete Estate Protection Ltd | Professional & scientific | 2019 |
| Complete Property Rentals Limited | Real estate | 2025 |
| Complete Property Revival Ltd | Construction | 2019 |
| Complete Property Solutions North East Limited | Construction | 2024 |
| Complete Security (Europe) Limited | Administrative & support | 1992 |
| Complex Construction and Demolition Ltd | Construction | 2025 |
| Complex Industrial Access Solutions (Offshore) Ltd | Construction | 2021 |
| Complex Industrial Access Solutions Ltd | Construction | 2016 |
| Complex Industrial Group Ltd | Construction | 2025 |
| Compliant Recruitment Ltd | Real estate | 2021 |
| Comprop North East Ltd | Hospitality | 2020 |
| Compropco Ltd | Real estate | 2019 |
| Concept London Consultancy Ltd | Real estate | 2024 |
| Conch Development Limited | Manufacturing | 2019 |
| Conesult Ltd | Professional & scientific | 2026 |
| Congreve Pizzeria Ltd | Hospitality | 2019 |
| Connaught Technical Limited | Professional & scientific | 2009 |
| Connolly C&I Limited | Professional & scientific | 2016 |
| Connolly Clinical Consultants Limited | Health & social care | 2013 |
| Connor & Co Shop Ltd | Wholesale & retail | 2025 |
| Connor Aesthetics Coaching Ltd | Other services | 2025 |
| Connor Carter Services Ltd | Transport & logistics | 2026 |
| Connor Wardle Welding Ltd | Professional & scientific | 2020 |
| Conor Construction Limited | Construction | 2004 |
| Constantin ION Logistics Limited | Transport & logistics | 2026 |
| Construction Company Ltd | Construction | 2025 |
| Construction Consultancy Cleveland Limited | Construction | 2020 |
| Construction Consultants NE Ltd | Professional & scientific | 2013 |
| Construction Control Solutions Limited | Professional & scientific | 2024 |
| Construction Factory Ltd | Construction | 2017 |
| Construction on Site David Ltd | Administrative & support | 2026 |
| Construction People Services Limited | Construction | 2019 |
| Construction Site Facilities Ltd | Construction | 2026 |
| Constructionwithcourtney Ltd | Construction | 2023 |
| Consult ASK Limited | Professional & scientific | 2014 |
| Consultancy HD Ltd | Professional & scientific | 2024 |
| Consultant Choice Apps (NE) Ltd | Administrative & support | 2015 |
| Consultants Choice Ltd | Administrative & support | 2020 |
| Contactless Payment Ltd | Wholesale & retail | 2022 |
| Contract OIL & GAS Inspections Ltd | Mining & quarrying | 2019 |
| Contrast UP Limited | Other services | 2026 |
| Control of Work Solutions Limited | Construction | 2025 |
| Controlworks Limited | Professional & scientific | 1988 |
| Convey Salons Ltd | Other services | 2017 |
| Convic Services Limited | Construction | 2022 |
| Conway Investment Group LLP | | 2026 |
| Cookes Logistics Ltd | Transport & logistics | 2026 |
| Cookies Competitions Ltd | Arts & recreation | 2025 |
| Cookkr Limited | Wholesale & retail | 2025 |
| Cooks Competitions Ltd | Arts & recreation | 2025 |
| Cooper Estates & Lettings Ltd | Real estate | 2025 |
| Coppersquare Roofing Ltd | Construction | 2025 |
| Corbyn Elec Ltd | Construction | 2020 |
| Cordell Carpentry and Joinery Limited | Manufacturing | 2023 |
| Core Asset Safeguard Solutions Ltd | Professional & scientific | 2025 |
| Core Integrity Limited | Professional & scientific | 2012 |
| Core Systems Software Ltd | Financial services | 2024 |
| Core Testing Ltd | Professional & scientific | 2019 |
| Corfield Quality Services Ltd | Professional & scientific | 2024 |
| Coriander (Teesside) Ltd | Hospitality | 2025 |
| Corners Electrical Limited | Construction | 2005 |
| Cornish Freelancing Ltd | Health & social care | 2024 |
| Corporate Cars Teesside Ltd | Transport & logistics | 2020 |
| Corporate Financial Services (UK) Limited | Financial services | 2007 |
| Corporation Estates Limited | Real estate | 2021 |
| Corrosure Ltd | Professional & scientific | 2026 |