| Conspector Limited | Construction | 2022 |
| Constantin Butu Ltd | Transport & logistics | 2020 |
| Construct Action Ltd | Real estate | 2025 |
| Constructa Services Limited | Construction | 2015 |
| Construction and Plant Assessments Ltd | Education | 2011 |
| Construction Savvy Ltd | Construction | 2024 |
| Construction Training Solutions Limited | Extraterritorial | 2009 |
| Consult 365 IT Solutions Ltd | Information & communication | 2018 |
| Consultingfirst-Holding Limited | Professional & scientific | 2006 |
| Container Yard Limited | Wholesale & retail | 2019 |
| Containerclad Limited | Manufacturing | 2018 |
| Containerwise Limited | Extraterritorial | 2023 |
| Containerwise Materials Handling Limited | Wholesale & retail | 2006 |
| Contemporary Lodge Living Ltd | Construction | 2022 |
| Contemporary Ritual Theatre Ltd | Administrative & support | 2019 |
| Contemporary Technologies Holding Ltd | Financial services | 2023 |
| Conti Services Ltd | Transport & logistics | 2026 |
| Conti Solutions Ltd | Transport & logistics | 2023 |
| Continental Gold East Lane Limited | Construction | 2023 |
| Continental Gold Hull Limited | Real estate | 2024 |
| Contour Safety Ltd | Professional & scientific | 2025 |
| Contract Cars Ltd | Wholesale & retail | 2018 |
| Contract Labour Solutions Ltd | Administrative & support | 2014 |
| Contract Management Solutions Limited | Administrative & support | 2003 |
| Contract Soft Furnishing Ltd | Manufacturing | 2021 |
| Contractors 4 Industry Ltd | Administrative & support | 2024 |
| Contractors Cosy Caves Ltd | Real estate | 2025 |
| Contrade Limited | Wholesale & retail | 2020 |
| Controlled Security Operations Ltd | Administrative & support | 2015 |
| Contura Stoves (UK) Limited | Wholesale & retail | 2020 |
| Converge Creations Limited | Manufacturing | 2025 |
| Conveyor Services Ltd | Professional & scientific | 2022 |
| Convocco Limited | Professional & scientific | 2012 |
| Conway Conservatories Ltd | Construction | 2014 |
| Cook Stars Doncaster South Ltd | Education | 2022 |
| Cooke & Company Financial Planning Ltd | Financial services | 2026 |
| Coolcare Yorkshire Limited | Administrative & support | 2024 |
| Coolmar Transport Limited | Transport & logistics | 2025 |
| Cooltruck Repair Ltd | Administrative & support | 2025 |
| Coombs Interiors Limited | Construction | 2005 |
| Cooockie Drive Ltd | Transport & logistics | 2019 |
| Coop's Plumbing and Heating Ltd | Construction | 2020 |
| Cooper Express Ltd | Transport & logistics | 2021 |
| Cooper QAS Ltd | Professional & scientific | 2025 |
| Cooper Rural Ltd | Professional & scientific | 2024 |
| Coopers Ventures Ltd | Wholesale & retail | 2020 |
| Cooplands ELG Ltd | Hospitality | 2025 |
| Coops Auto Solutions Ltd | Wholesale & retail | 2019 |
| Copley Management Ltd | Professional & scientific | 2023 |
| Copper Badger Ltd | Extraterritorial | 2026 |
| Copper Finch Ventures Limited | Extraterritorial | 2026 |
| Copper Kite Holdings Ltd | Extraterritorial | 2026 |
| Coppice Close Management Limited | Real estate | 2017 |
| COR Reformer Studio Ltd | Arts & recreation | 2026 |
| Coral Duvet Ltd | Real estate | 2025 |
| Coraldrive Ltd | Transport & logistics | 2022 |
| Coralva Limited | Transport & logistics | 2025 |
| Cordova Property Group Ltd | Real estate | 2026 |
| Core Admin Services Ltd | Administrative & support | 2025 |
| Core Hire Limited | Financial services | 2025 |
| Core Renovation Ltd | Construction | 2019 |
| Corehaul Logistics Ltd | Transport & logistics | 2025 |
| Corepoint ALL Services Ltd | Transport & logistics | 2025 |
| Coreter Limited | Information & communication | 2016 |
| Corextraders Ltd | Wholesale & retail | 2025 |
| Coriel Orthopaedic Group LLP | | 2020 |
| Coriel Orthopaedics Group Ltd | Health & social care | 2022 |
| Cormorant Survey (UK) Limited | Administrative & support | 2010 |
| Cornea.Log Ltd | Transport & logistics | 2023 |
| Cornel Transport Limited | Transport & logistics | 2015 |
| Cornel-Gheti Ltd | Transport & logistics | 2023 |
| Corner Saver Ltd | Wholesale & retail | 2026 |
| Cornerstone Homes Doncaster Ltd | Real estate | 2021 |
| Cornerstone Jewellers (Bolsover) Limited | Wholesale & retail | 2010 |
| Cornerstone Jewellers Limited | Wholesale & retail | 1999 |
| Cornerstone Structures Ltd | Extraterritorial | 2026 |
| Cornerstone YML Trustee Limited | Other services | 2025 |
| Cornholme Property Ltd | Hospitality | 2020 |
| Corntree Limited | Wholesale & retail | 2024 |
| Cornwall Avenue Management Limited | Real estate | 2008 |
| Corona Sunbeds Ltd | Administrative & support | 2018 |
| CORPOR8 Tech Solutions Ltd | Agriculture & fishing | 2021 |
| Corporate Services Group Ltd | Administrative & support | 2009 |
| Corral Grove Residents Management Company Limited | Households | 2026 |
| Corvanta Ltd | Information & communication | 2026 |
| Corvid Maintenance Ltd | Administrative & support | 2025 |
| Corvis Communications Limited | Professional & scientific | 2018 |
| COS Logistics Ltd | Transport & logistics | 2024 |
| Cosge Ltd | Transport & logistics | 2023 |
| Cosgrove Cafe Limited | Hospitality | 2018 |
| Cosma Logistic Ltd | Transport & logistics | 2025 |
| Cosmic Beauty Ltd | Wholesale & retail | 2025 |
| Cosmic Brushes Ltd | Manufacturing | 2017 |
| Costcutter Balby Ltd | Wholesale & retail | 2019 |
| Costel Norocosu Ltd | Wholesale & retail | 2023 |
| Costi Builder Ltd | Construction | 2026 |
| Cosyhome Insulation Limited | Construction | 1976 |
| Cotton & Butler Limited | Construction | 2005 |
| Couch Concrete Ltd | Manufacturing | 2024 |
| Couch Developments Limited | Construction | 2022 |