| Computer Solutions (Winchester) Limited | Information & communication | 2003 |
| CON Air Installations Ltd | Energy | 2011 |
| Conan Doyle Estate Limited | Professional & scientific | 2005 |
| Concannon Medical Limited | Health & social care | 2014 |
| Concept 20 Architecture Ltd | Professional & scientific | 2020 |
| Concept Cad/Cam Ltd | Manufacturing | 2008 |
| Concept Design Limited | Extraterritorial | 2006 |
| Concept Power Ltd | Professional & scientific | 2019 |
| Concept Security Solutions Ltd | Administrative & support | 2019 |
| Concept Yachts Shipyard Limited | Manufacturing | 2023 |
| Concerto Group Limited | Other services | 1986 |
| Concierge Marine Logistics Limited | Transport & logistics | 2026 |
| Concorde Analytics Ltd | Information & communication | 2022 |
| Concorde Designs Limited | Professional & scientific | 2026 |
| Concorde Enterprises Ltd | Professional & scientific | 2024 |
| Concordia Commercial Solutions Limited | Professional & scientific | 2005 |
| Concourse Yachts LLP | | 2006 |
| Conditor Holdings Ltd | Construction | 2025 |
| Conditor Ltd | Construction | 2025 |
| Conditor Management Ltd | Construction | 2025 |
| Conditor Project X Ltd | Construction | 2025 |
| Conduire Collective Ltd | Wholesale & retail | 2025 |
| Conex Holdings Limited | Financial services | 2023 |
| Confederation of Vehicle Testing Stations Ltd | Administrative & support | 2020 |
| Confetti & Lace Bridal Ltd | Wholesale & retail | 2026 |
| Confido Consulting Services Limited | Professional & scientific | 2022 |
| Configwise Limited | Information & communication | 2025 |
| Conifer Court Flat Management Ltd | Households | 2006 |
| Conjuncti Consulting Ltd | Information & communication | 2020 |
| Conker Coffee Ltd | Hospitality | 2018 |
| Conker Tree Ltd | Manufacturing | 2021 |
| Connaught Place (Brockenhurst) Management Company Limited | Households | 2024 |
| Connaught View Limited | Real estate | 2017 |
| Connect 24 Care Ltd | Administrative & support | 2020 |
| Connect 4 UK Limited | Information & communication | 2025 |
| Connect Carpentry Ltd | Construction | 2024 |
| Connect Consultancy Ltd. | Professional & scientific | 2002 |
| Connect Live Media Ltd | Other services | 2026 |
| Connected Electrical Limited | Construction | 2010 |
| Connected Fire & Security Limited | Construction | 2011 |
| Conquer Tables Ltd | Manufacturing | 2023 |
| Conrad Murphy Consulting Limited | Health & social care | 2010 |
| Conroy Court RTM Company Ltd | Households | 2011 |
| Conservatory Eco Roofs Ltd | Construction | 2014 |
| Conservatory Insulation Specialists Limited | Construction | 2020 |
| Considerate Carnivore Ltd | Wholesale & retail | 2021 |
| Consilium Partners Limited | Professional & scientific | 2014 |
| Consolute RPD Limited | Professional & scientific | 2015 |
| Consop Ltd | Construction | 2019 |
| Consortio Recruitment Group Ltd | Administrative & support | 2020 |
| Consortio RG Ltd | Administrative & support | 2014 |
| Consortio Search Ltd | Administrative & support | 2025 |
| Construct Lettings Ltd | Real estate | 2020 |
| Construct-Lab Ltd. | Construction | 2015 |
| Constructii Denis Ltd | Construction | 2022 |
| Construction & Civil Site Services Ltd | Water & waste | 2011 |
| Construction 13 Limited | Construction | 2017 |
| Construction 3D Ltd | Construction | 2022 |
| Construction Co Services Ltd | Construction | 2026 |
| Construction Southern Ltd | Construction | 2015 |
| Constructions MAX Ltd | Construction | 2017 |
| Consult Circle Ltd | Wholesale & retail | 2016 |
| Consult Communications Ltd | Professional & scientific | 2019 |
| Consult Limited | Administrative & support | 1989 |
| Consult Point Limited | Professional & scientific | 2025 |
| Consultan Limited | Professional & scientific | 2025 |
| Consultancy AI Limited | Information & communication | 2025 |
| Consultancy.Com Limited | Professional & scientific | 2008 |
| Consultbim Limited | Professional & scientific | 2018 |
| Consulting Engineers Group UK Ltd | Professional & scientific | 2023 |
| Consulting Firm Ltd | Professional & scientific | 2020 |
| Consurv Ltd | Professional & scientific | 2009 |
| Container Fumigation Services Limited | Water & waste | 2003 |
| Container Maintainer Group Ltd | Manufacturing | 2026 |
| Container Services (Solent) Limited | Manufacturing | 1999 |
| Containerhaul Limited | Transport & logistics | 1971 |
| Contaxial Ltd | Wholesale & retail | 2015 |
| Contemporary Slate and Stone Limited | Manufacturing | 2019 |
| Content Labs Copywriting Services Ltd | Information & communication | 2017 |
| Contexts.Live Ltd | Information & communication | 2021 |
| Contility Ltd | Information & communication | 2023 |
| Continental Estate Ltd | Real estate | 2024 |
| Continuity Dance Company Ltd | Education | 2023 |
| Continuous Guttering South Coast Limited | Extraterritorial | 2002 |
| Contista Media Ltd | Information & communication | 2014 |
| Contract Analytical Services Ltd. | Professional & scientific | 2011 |
| Contracting Consultancy UK Ltd | Construction | 2006 |
| Contracting Site Services Limited | Professional & scientific | 2010 |
| Contractor Plus Ltd | Administrative & support | 2025 |
| Conversion Lounge Ltd | Information & communication | 2025 |
| Convoi Exceptionnel Ltd | Transport & logistics | 1998 |
| Conycare Ltd | Construction | 2018 |
| Cooked to Perfection Ltd | Hospitality | 2018 |
| Cookham Home Delivery and Takeaway Ltd | Wholesale & retail | 2024 |
| Cooks (Croydon) Limited | Real estate | 1951 |
| Cool Clear Water Ltd | Extraterritorial | 2023 |
| Cool IOT Ltd | Information & communication | 2022 |
| Cool Living Limited | Construction | 2016 |
| Cool Living Stewartby Limited | Construction | 2016 |
| Cool-Gauge Limited | Administrative & support | 2021 |