| C T Warner (Grimsby) Limited | Wholesale & retail | 2003 |
| C W Sutton Limited | Construction | 2007 |
| C&A Connections Ltd | Financial services | 2026 |
| C&E Independent Technical Services Limited | Professional & scientific | 2007 |
| C&G Lesuire Limited | Arts & recreation | 2019 |
| C&H Brewster Limited | Real estate | 2024 |
| C&J Group (Lincs) Limited | Wholesale & retail | 2020 |
| C&T Property Group Ltd | Real estate | 2023 |
| C. Carty Limited | Wholesale & retail | 2003 |
| C.A. Norman Plumbing Limited | Construction | 2003 |
| C.A.D.E Electrical Contractors Limited | Construction | 2001 |
| C.A.T. Construction (South Humberside) Limited | | 1983 |
| C.F. Thompson & SON (Grimsby) Limited | Construction | 2002 |
| C.J. Hair Design Limited | Other services | 2004 |
| C.J.M. Cottingham Limited | Professional & scientific | 1954 |
| C.Mcintosh Wind Ltd | Construction | 2018 |
| C.Patchett & Son(Lincs.)Limited | Agriculture & fishing | 1957 |
| C.T.D. Enterprises Ltd | Other services | 2011 |
| C.W. and a. Suthrell Limited | Real estate | 1964 |
| CA Mechanical Ltd | Manufacturing | 2026 |
| CA Online Trading Ltd | Wholesale & retail | 2022 |
| Ca&Sh Lettings Ltd | Real estate | 2021 |
| Cab's 4 Cabbys Ltd | Administrative & support | 2025 |
| Caba Trans Ltd | Transport & logistics | 2023 |
| Cable Network & Accessories Ltd | Information & communication | 2009 |
| CAD Flow Engineering Ltd | Professional & scientific | 2025 |
| CAD Services MK Limited | Construction | 2011 |
| Cadserv Limited | Professional & scientific | 2017 |
| CAG Developments Ltd | Construction | 2016 |
| CAG Property Holdings Limited | Real estate | 2016 |
| Cain 9 Services Ltd | Transport & logistics | 2018 |
| Caistor Mews Limited | Households | 2002 |
| Caistorestates Ltd | Administrative & support | 2019 |
| Callaghan Site Services Ltd | Construction | 2018 |
| Callmac Holdings Limited | Professional & scientific | 2008 |
| Callmac Scaffolding (UK) Limited | Construction | 2005 |
| Calm Attire Holdings Limited | Manufacturing | 2017 |
| Calm Attire Limited | Manufacturing | 2010 |
| Calm Attire QP Ltd | Real estate | 2024 |
| Calm Attire Residential Limited | Real estate | 2021 |
| Cambrian Climate Solutions Ltd | Construction | 2025 |
| Cambridge Estate Agents Limited | Real estate | 2000 |
| Camelot Ventures (UK) Ltd | Wholesale & retail | 2013 |
| Campden Kids Limited | Health & social care | 2015 |
| Candle Light Gardens Ltd | Other services | 2019 |
| Cane Homes Limited | Construction | 2019 |
| Canel Solutions CIC | Administrative & support | 2022 |
| Caninecreations Ltd | Other services | 2023 |
| Canis Engineering Ltd | Manufacturing | 2015 |
| Capela Group Holding Ltd | Financial services | 2020 |
| CAPITOL76 Leisure Ltd | Hospitality | 2024 |
| Car Clinic Grimsby Limited | Wholesale & retail | 2022 |
| Car Consultants (GY) Limited | Manufacturing | 2005 |
| CAR149 Ltd | Transport & logistics | 2023 |
| Carcaptain Limited | Education | 2010 |
| Carchar Limited | Health & social care | 2021 |
| Card Brothers Limited | Wholesale & retail | 2025 |
| Cardestra Premier Cleaning and Facility Management Ltd | Administrative & support | 2026 |
| Cardlaser Limited | Information & communication | 1999 |
| Care Plus Group Charitable Trust | Health & social care | 2015 |
| Care Plus Group Primary Care Ltd | Health & social care | 2007 |
| Careben Ltd | Health & social care | 2023 |
| Cargo X Ltd | Transport & logistics | 2024 |
| Cargoroute Logistics Ltd | Transport & logistics | 2026 |
| Carl Glover Ltd | Hospitality | 2019 |
| Carling-Mayer-Properties Ltd | Real estate | 2025 |
| Carmand Ltd | Health & social care | 2010 |
| Carnforth Parade OFF Licence Ltd | Wholesale & retail | 2013 |
| Carol Trans Ltd | Transport & logistics | 2019 |
| Carpet Gallery Grimsby Limited | Construction | 2025 |
| Carpet Runners Ltd. | Extraterritorial | 2018 |
| Carpetbase Limited | Wholesale & retail | 2010 |
| Carr Development Consultancy Limited | Professional & scientific | 2016 |
| Carrera Engineering Holdings Limited | Financial services | 2025 |
| Carrera Engineering Services Limited | Professional & scientific | 2006 |
| Carrot Events Limited | Other services | 2016 |
| Cars of Grimsby Ltd | Other services | 2012 |
| Cartech (Lincs) Limited | Wholesale & retail | 2019 |
| Carter Wilson Industrial Ltd | Households | 2011 |
| Cash OUT Motors Limited | Wholesale & retail | 2025 |
| Cash Registers (Grimsby) Limited | Wholesale & retail | 1978 |
| Cashswaps Limited | Wholesale & retail | 2025 |
| Casi Trans Ltd | Transport & logistics | 2023 |
| Caspian Filter Technology Ltd | Manufacturing | 2004 |
| Cast Iron Air Brick Company Limited | Wholesale & retail | 2010 |
| Cast Vehicle Solutions Ltd | Wholesale & retail | 2014 |
| Castle Hotel Services Limited | Administrative & support | 2005 |
| Castleton Project Management Ltd | Construction | 2016 |
| Castspro Limited | Arts & recreation | 2023 |
| Catalin Trans Ltd | Transport & logistics | 2026 |
| CATCH22 by David Chamberlain Ltd | Hospitality | 2024 |
| Catchacloud Ltd | Construction | 2022 |
| Catermac Durham Limited | Hospitality | 2016 |
| Cathedral Limited | Wholesale & retail | 2019 |
| Catherine James Lettings Limited | Professional & scientific | 2010 |
| Cave Enterprises Limited | Other services | 2018 |
| Caveman Cookery Ltd | Hospitality | 2019 |
| Cavendish Auto Service Ltd | Wholesale & retail | 2025 |
| Cavendish Dental Ltd | Health & social care | 2014 |
| Cavplus Ltd | Construction | 2024 |