| Confident Sage Ltd | Information & communication | 2010 |
| Confidential Solutions Group Ltd | Financial services | 2002 |
| Confidential Solutions Limited | Financial services | 2001 |
| Configured Platforms Ltd | Construction | 2018 |
| Conflux Digital Ltd | Information & communication | 2017 |
| Conflux Global Ltd | Information & communication | 2021 |
| Conform Contracting Ltd | Construction | 2018 |
| Conformedia Holdings Ltd | Financial services | 2023 |
| Conformedia Systems Limited | Information & communication | 2008 |
| Confort Care Limited | Wholesale & retail | 2024 |
| Confyhair Limited | Wholesale & retail | 2026 |
| Congregate Ltd | Information & communication | 2010 |
| Congregational Insurance Solutions Limited | Financial services | 2017 |
| Coni Lighting Limited | Arts & recreation | 2010 |
| Conjunction Software Ltd | Information & communication | 2019 |
| Conker Tree House Ltd | Real estate | 2022 |
| Conlon Flooring Ltd | Construction | 2024 |
| Connaught Construction Limited | Construction | 2009 |
| Connaught Developments Ltd. | Administrative & support | 2018 |
| Connaught Property Investments Limited | Real estate | 2014 |
| Connect in the North | Health & social care | 1995 |
| Connect Roads Cambridgeshire Holdings Limited | Professional & scientific | 2010 |
| Connect Roads Cambridgeshire Intermediate Limited | Administrative & support | 2010 |
| Connect Roads Cambridgeshire Limited | Administrative & support | 2010 |
| Connect Roads Coventry Holdings Limited | Administrative & support | 2010 |
| Connect Roads Coventry Intermediate Limited | Administrative & support | 2010 |
| Connect Roads Coventry Limited | Administrative & support | 2010 |
| Connect Roads Northamptonshire Holdings Limited | Professional & scientific | 2010 |
| Connect Roads Northamptonshire Intermediate Limited | Administrative & support | 2010 |
| Connect Roads Northamptonshire Limited | Administrative & support | 2010 |
| Connect Roads South Tyneside Holdings Limited | Professional & scientific | 2005 |
| Connect Roads South Tyneside Limited | Administrative & support | 2005 |
| Connect Roads Sunderland Holdings Limited | Professional & scientific | 2003 |
| Connect Roads Sunderland Limited | Administrative & support | 2003 |
| Connect the Dots Bradford Community Interest Company | Health & social care | 2023 |
| Connect Wills Limited | Professional & scientific | 2013 |
| Connect With Taar Ltd | Wholesale & retail | 2025 |
| Connect Yorkshire | Administrative & support | 2001 |
| CONNECT2EDEN Limited | Administrative & support | 2020 |
| Connected Werks Limited | Information & communication | 2018 |
| Connecting Excellence Group PLC | Financial services | 2025 |
| Connecting London Limited | Information & communication | 1983 |
| Connection GAS Kitchen and Bathroom Ltd | Other services | 2015 |
| Connections Care Limited | Health & social care | 2015 |
| Connective Global Ltd | Information & communication | 2023 |
| CONNECTIVE3 Group Limited | Financial services | 2026 |
| CONNECTIVE3 Limited | Professional & scientific | 2019 |
| Connector Group Limited | Professional & scientific | 2024 |
| Connector Subsea Power Systems Ltd | Manufacturing | 2026 |
| Connolly Broadley a D Limited | Construction | 2023 |
| Connolly Broadley Group Limited | Construction | 2015 |
| Connor Brassington Limited | Information & communication | 2020 |
| Connoratkinsonlad Ltd | Professional & scientific | 2024 |
| Conqueror Racing Ltd | Administrative & support | 1995 |
| Conrad Davies Company Limited | Arts & recreation | 2003 |
| Conscious Financial Planning Ltd | Professional & scientific | 2022 |
| Conscious Gains Ltd | Education | 2023 |
| Conscious Properties Limited | Real estate | 1999 |
| Conservatec Ltd | Manufacturing | 1998 |
| Conservation & Development Appraisal Limited | Professional & scientific | 1990 |
| Conservatory Roof Insulators Limited | Construction | 2014 |
| Conservatory Roof Supplies Limited | Manufacturing | 2004 |
| Consilia Legal Leeds Limited | Professional & scientific | 2015 |
| Consilia Mediation Limited | Other services | 2020 |
| Consilio Marketing Ltd | Professional & scientific | 2018 |
| Consilium Estates Ltd | Professional & scientific | 2013 |
| Consistent Logistics Ltd | Transport & logistics | 2024 |
| Console Portal Ltd | Manufacturing | 2018 |
| Consort Homes Limited | Extraterritorial | 2014 |
| Consort Motorhomes Ltd | Wholesale & retail | 2019 |
| Conspire Coaching Associates Limited | Education | 2017 |
| Constance Heath Ltd | Other services | 2026 |
| Constant Systems (Holdings) Limited | Financial services | 2021 |
| Constantin Clean Limited | Administrative & support | 2023 |
| Constone Court (Leeds) Management Company Ltd | Real estate | 2013 |
| Construct AIQ Limited | Information & communication | 2025 |
| Construct Build Renovate Ltd | Construction | 2025 |
| Construct Interiors Developments Limited | Construction | 2022 |
| Construct IQA Limited | Information & communication | 2025 |
| Construct Logic Limited | Information & communication | 2025 |
| Construct PM Ltd | Professional & scientific | 2022 |
| Construct&Cleaning Ltd | Construction | 2025 |
| Constructing Rainbows Ltd | Professional & scientific | 2017 |
| Construction & Cleaning Services Ltd | Construction | 2025 |
| Construction Builder Solution Ltd | Education | 2025 |
| Construction Card Support Ltd | Other services | 2025 |
| Construction Dynamics (North) Ltd | Construction | 2019 |
| Construction Fast and Safety Ltd | Construction | 2025 |
| Construction Marine Limited | Construction | 1986 |
| Construction Time Limited | Construction | 2021 |
| Constructions 4U Ltd | Construction | 2025 |
| Constructive Futures CIC | Other services | 2024 |
| Consult Create Ltd | Professional & scientific | 2017 |
| Consult DJH Limited | Construction | 2008 |
| Consult Lhasa Limited | Information & communication | 2023 |
| Consult Search & Selection Ltd | Administrative & support | 2009 |
| Consultancy Bussiness Ltd | Professional & scientific | 2024 |
| Consultant Dermatology Alliance LLP | | 2026 |
| Consultant Pain Interventions Limited | Health & social care | 2021 |
| Consultants Insight Academy Limited | Information & communication | 2025 |