| Corseva Ltd | Information & communication | 2026 |
| Cosalt Caravans Limited | Extraterritorial | 1941 |
| Cosmetic Dental Centre Limited | Health & social care | 2008 |
| Cosmina Transport Ltd | Transport & logistics | 2025 |
| Coson Commercial Ltd | Professional & scientific | 2021 |
| Coson IT Services Ltd | Information & communication | 2020 |
| Costi Distribution Limited | Transport & logistics | 2022 |
| Cotis Developments Limited | Construction | 2018 |
| Cotis Properties Limited | Construction | 2007 |
| Cotter Construction Ltd | Construction | 2014 |
| Coulson & Co Engineering Limited | Professional & scientific | 2026 |
| Countryside Clearances Limited | Transport & logistics | 2022 |
| Countryside Pursuits Limited | Wholesale & retail | 2017 |
| County Fisheries Ltd | Wholesale & retail | 2021 |
| Courageous Minds Ltd | Health & social care | 2025 |
| Covletz Ltd | Real estate | 2019 |
| Cowan Aesthetic Consulting Ltd | Professional & scientific | 2018 |
| Cowes Town Central Limited | Wholesale & retail | 2018 |
| COX Holdings Group Ltd | Financial services | 2025 |
| COX Industrial Services Ltd | Construction | 2023 |
| CP Vintage Limited | Wholesale & retail | 2019 |
| CPE Maintenance Limited | Construction | 2019 |
| CPW Engineering Ltd | Construction | 2019 |
| Crafted London Ltd | Construction | 2016 |
| Craftex Investments Ltd | Arts & recreation | 2017 |
| Craftsman Style Ltd | Wholesale & retail | 2017 |
| Craig Brabben Building Contractor Limited | Construction | 2005 |
| Craig Jarman Services Limited | Other services | 2009 |
| Craig Mckay Limited | Professional & scientific | 2012 |
| Cravenglow Consultants Limited | Professional & scientific | 1981 |
| CRE8TIVE Decor Ltd | Arts & recreation | 2019 |
| Creations Hair & Beauty Limited | Other services | 2018 |
| Creative Start Arts in Health C.I.C. | Arts & recreation | 2012 |
| Credo Delivery Ltd | Transport & logistics | 2022 |
| Cress Cottage Equine Limited | Arts & recreation | 2022 |
| CRG Research & Development Limited | Professional & scientific | 2010 |
| Crinatrans Ltd | Transport & logistics | 2016 |
| Crisis Therapeutic Solutions Ltd | Health & social care | 2022 |
| Cristea George-Romeo Ltd | Transport & logistics | 2018 |
| Cristi Ionut Trans Ltd | Transport & logistics | 2023 |
| CRM Engineering Limited | Professional & scientific | 2023 |
| CRM Refrigeration Ltd | Construction | 2019 |
| CRN Services Limited | Professional & scientific | 2020 |
| Croftmill Trading Limited | Wholesale & retail | 2011 |
| Croissant Properties Limited | Real estate | 2012 |
| Cromwell Pizza Ltd | Hospitality | 2025 |
| Crosskills Florists Limited | Wholesale & retail | 2013 |
| Crossy's Cabs Limited | Transport & logistics | 2018 |
| Crown Catering (Lincs) Limited | Hospitality | 2017 |
| Crown Dental Ltd | Health & social care | 2018 |
| CROWN34 Limited | Manufacturing | 2015 |
| CRS Couriers Ltd | Transport & logistics | 2025 |
| Crsh Group Ltd | Real estate | 2024 |
| Cryo Coldstore Limited | Transport & logistics | 2023 |
| Cryotech (Grimsby) Limited | Professional & scientific | 2003 |
| Cryptek Web Design Limited | Information & communication | 2024 |
| Crystal Double Glazing (Grimsby) Limited | Construction | 2002 |
| CS Access and Coatings Limited | Construction | 2025 |
| CS Motor Services Limited | Wholesale & retail | 2017 |
| CS39 Limited | Real estate | 2015 |
| CS39 Services Limited | Real estate | 2025 |
| CSC IT Consultancy Limited | Professional & scientific | 2012 |
| Csenergy Ltd | Administrative & support | 2024 |
| CSH Management Services Ltd | Administrative & support | 2016 |
| CT Holdings (Grimsby) Ltd | Professional & scientific | 2022 |
| CT Roofing Specialists Limited | Construction | 2020 |
| CTV Studios Limited | Information & communication | 2012 |
| Cubs and Kids Limited | Education | 2023 |
| Cudox Wellbeing C.I.C. | Health & social care | 2020 |
| Cuff & Co Limited | Construction | 2003 |
| Cuisine Hub Ltd | Information & communication | 2025 |
| Culleys Carrys Ltd | Transport & logistics | 2025 |
| Cupid Cars Limited | Transport & logistics | 2017 |
| Cupis Orchard Estates Limited | Households | 2002 |
| Curated Edit Ltd | Professional & scientific | 2025 |
| Cursaru Cleaning Ltd | Administrative & support | 2019 |
| Curtis Way Management Company Limited | Administrative & support | 2008 |
| Custom Coatings & Maintenance Ltd | Construction | 2022 |
| Custom Prezzie Ltd | Wholesale & retail | 2020 |
| Cuticle Counter Limited | Other services | 2019 |
| Cutting Edge Wind Consultants Ltd | Professional & scientific | 2023 |
| CVF Holding UK Limited | Extraterritorial | 2017 |
| CVS Assets Limited | Real estate | 2022 |
| CWR Engineering Limited | Professional & scientific | 2009 |
| Cyber-Skynet Ltd | Information & communication | 2017 |
| Cyberdefcon Limited | Information & communication | 2007 |
| Cycle Bars Limited | Hospitality | 2018 |
| Cycle Hub Lincs C.I.C. | Wholesale & retail | 2013 |
| Cyclefan Limited | Professional & scientific | 2004 |
| Cyclops Engineering Europe Limited | Professional & scientific | 2018 |
| Cyden Homes Limited | Real estate | 1962 |
| Cygnet Aesthetics Ltd | Other services | 2021 |
| Cygnet Manor Management Limited | Households | 2026 |
| Cytofusion Limited | Financial services | 2014 |
| CYZ (Greenwich) Limited | Real estate | 2002 |
| CYZ Limited | Real estate | 1995 |
| D & BJ Services Limited | Professional & scientific | 2005 |
| D & D Fascia and Window Systems Limited | Construction | 2010 |
| D & D Grimsby Ltd | Real estate | 2021 |
| D & G Heating & Plumbing Services (Lincs) Ltd | Construction | 2016 |