| Compliance Training Services Limited | Public administration | 2005 |
| COMPLIANCE4U Ltd | Professional & scientific | 2023 |
| Compliant Labs Ltd | Administrative & support | 2026 |
| Compliant Retrofits Ltd | Construction | 2025 |
| Compliant Technology Systems Ltd | Information & communication | 2018 |
| Comply Limited | Wholesale & retail | 2002 |
| Complyed Futures C.I.C. | Education | 2025 |
| Complyed Holdings Limited | Financial services | 2025 |
| Complyed Limited | Education | 2024 |
| Composite Doors Ltd | Manufacturing | 2024 |
| Comprehending Education Limited | Education | 2023 |
| Comprehensive Care Ltd | Health & social care | 2016 |
| Comprehensive Decorating Ltd | Construction | 2009 |
| Compudos Limited | Wholesale & retail | 2011 |
| Computastore Limited | Information & communication | 1978 |
| Computek Itad Ltd | Information & communication | 2025 |
| Computek Technologies Limited | Wholesale & retail | 2022 |
| Computer Bargains Limited | Wholesale & retail | 1996 |
| Computer Career Centre | Other services | 2025 |
| Computer Chap Ltd | Other services | 2024 |
| Computer Monitoring and Control Limited | Manufacturing | 1988 |
| Computer Picture Company Limited | Information & communication | 1994 |
| Computer Recycling Solutions Ltd | Information & communication | 2003 |
| Computer Recycling Technology Ltd | Information & communication | 2020 |
| Computer Software & Peripherals Limited | Information & communication | 1996 |
| Computers and Network Consultants Limited | Information & communication | 1998 |
| Computers UK Limited | Information & communication | 1998 |
| Computingw Ltd | Information & communication | 2013 |
| Comrco Ltd | Wholesale & retail | 2025 |
| Comstar Services Limited | Information & communication | 2009 |
| Comsum Limited | Administrative & support | 2018 |
| Comtegrate Ltd | Information & communication | 2026 |
| Comvera for Import Ltd | Wholesale & retail | 2025 |
| Comyns Limited | Professional & scientific | 1993 |
| Comyns of London Limited | Professional & scientific | 1993 |
| CON Mech Durham 2 Limited | Manufacturing | 1988 |
| Conal JAY Media Limited | Professional & scientific | 2024 |
| Conall Gormley Ltd | Arts & recreation | 2021 |
| Conato Ltd | Wholesale & retail | 2021 |
| Conatus Group Limited | Information & communication | 2011 |
| Conb Ltd | Construction | 2024 |
| Conbini Ltd | Wholesale & retail | 2018 |
| Concare Fire Services Limited | Manufacturing | 2011 |
| Concept 888 Ltd | Administrative & support | 2025 |
| Concept and Vision Ltd | Administrative & support | 2026 |
| Concept Assist Limited | Administrative & support | 2018 |
| Concept Automotive Limited | Financial services | 2003 |
| Concept Building Services North West Ltd | Construction | 2017 |
| Concept Car Credit Limited | Wholesale & retail | 2004 |
| Concept Chemicals and Coatings Limited | Manufacturing | 1987 |
| Concept Chemicals Ltd | Extraterritorial | 2017 |
| Concept Consulting Engineers Limited | Professional & scientific | 2022 |
| Concept Developments (M/Cr) Ltd. | Real estate | 2011 |
| Concept Environmental Solutions Limited | Water & waste | 2013 |
| Concept Foundry Limited | Wholesale & retail | 2011 |
| Concept Funerals Limited | Extraterritorial | 2011 |
| Concept GAS Ltd | Construction | 2019 |
| Concept Heating Systems Limited | Construction | 1999 |
| Concept Infrastructure Technology Group Ltd | Information & communication | 2024 |
| Concept Joinery Limited | Construction | 2003 |
| Concept Joinery NW Limited | Construction | 2021 |
| Concept Living Group Ltd | Real estate | 2023 |
| Concept Properties & Finance Ltd | Real estate | 2009 |
| Concept Styling Ltd | Wholesale & retail | 2026 |
| Concept Technologies Limited | Wholesale & retail | 2018 |
| Conceptgalore Limited | Wholesale & retail | 2025 |
| Conceptial Development 1 Ltd | Construction | 2020 |
| Concert Promoters Association Limited(The) | Other services | 1986 |
| Concertus Ltd | Professional & scientific | 2020 |
| Concession Solutions Ltd | Wholesale & retail | 2025 |
| Conciairge Aviation Ltd | Transport & logistics | 2022 |
| Concierge Property Ltd | Real estate | 2019 |
| Concierge Seven Limited | Other services | 2017 |
| Concileg Ltd | Wholesale & retail | 2015 |
| Conciliate Developments Ltd | Real estate | 2016 |
| Conciliate Projects Ltd | Real estate | 2016 |
| Concise Financial Services Ltd | Financial services | 2018 |
| Conclusive Financial Limited | Financial services | 2013 |
| Conclusive Property Services Ltd | Construction | 2015 |
| Concor Limited | Extraterritorial | 2006 |
| Concord House Management (Birmingham) Limited | Households | 2014 |
| Concorde Overseas Logistics and Trade Limited | Administrative & support | 2017 |
| Concorde Realty Limited | Real estate | 2025 |
| Concorde Solutions Limited | Administrative & support | 2025 |
| Concordus Ltd | Professional & scientific | 2020 |
| Concrete Tomato Estates Ltd | Real estate | 2025 |
| Concrete Winning Ltd | Information & communication | 2024 |
| Condensed Cooling Ltd | Energy | 2018 |
| Condition (U.K) Ltd | Wholesale & retail | 2020 |
| Conditional Effect. CIC | Wholesale & retail | 2026 |
| Conditor Asset Management Limited | Professional & scientific | 2019 |
| Condron Decorating Limited | Construction | 2018 |
| Condron Design Consultants Limited | Other services | 2016 |
| Conduce Marketing Limited | Professional & scientific | 2020 |
| Conductr Ltd | Professional & scientific | 2022 |
| Conductr Originals Ltd | Hospitality | 2025 |
| Conduit Investments Limited | Real estate | 2023 |
| Conduk Ltd | Construction | 2022 |
| Condurre Clothing Ltd | Wholesale & retail | 2018 |
| Coney Island Creative Ltd | Professional & scientific | 2025 |