| Connect CEE Limited | Professional & scientific | 2009 |
| Connect Commercial Property Ltd | Real estate | 2026 |
| Connect Digital Ltd | Other services | 2013 |
| Connect Electrical Services (SW) Limited | Construction | 2024 |
| Connect KIN CIC | Education | 2024 |
| Connect Property (SW) Limited | Real estate | 2024 |
| Connect Property Solutions (SW) Ltd | Real estate | 2024 |
| Connect Wellbeing in Education LLP | | 2022 |
| Connected Competitions Ltd | Information & communication | 2021 |
| Connected Light Holdings Limited | Financial services | 2023 |
| Connected Light Limited | Extraterritorial | 2016 |
| Connected Network Solutions Ltd | Information & communication | 2013 |
| Connecting Lines Ltd | Information & communication | 2019 |
| Connecting Mindfully Ltd | Health & social care | 2024 |
| Connections FZE Ltd | Professional & scientific | 2019 |
| Connell-Waite Co Ltd | Administrative & support | 2024 |
| Connexion Developments Limited | Manufacturing | 1998 |
| Connexions Executive Travel Limited | Transport & logistics | 2025 |
| Connexions West of England Limited | Extraterritorial | 2000 |
| Connolly & Callaghan Group Limited | Professional & scientific | 2016 |
| Connolly & Callaghan Limited | Real estate | 1999 |
| Connolly & Callaghan Refurbishments Limited | Construction | 2017 |
| Connolly and Callaghan Investments Ltd | Real estate | 2004 |
| Connolly Scaffolding and Rigging Limited | Information & communication | 2015 |
| Connolly Wellingham Ltd | Professional & scientific | 2016 |
| Conor Mccormack Enterprise Ltd | Professional & scientific | 2023 |
| Conor Moloney Media Ltd | Information & communication | 2022 |
| Conquer Ltd | Real estate | 2007 |
| Conquest Coaching Ltd | Health & social care | 2025 |
| Conrad Group Ltd | Professional & scientific | 2025 |
| Conrad Tate Advisory Limited | Professional & scientific | 2022 |
| Conran Carpets Ltd | Wholesale & retail | 2018 |
| Conscian Pictures Ltd | Information & communication | 2020 |
| Conscience Foods and Lifestyle Limited | Wholesale & retail | 2019 |
| Conscious Accessories Ltd | Extraterritorial | 2022 |
| Conscious Health & Home Ltd | Wholesale & retail | 2003 |
| Conscious Solutions Group Ltd | Information & communication | 2018 |
| Conscious Solutions Limited | Information & communication | 2003 |
| Conservativesvoicesme Ltd | Extraterritorial | 2025 |
| Conservativevoiceltdme.Uk Ltd | Extraterritorial | 2025 |
| Consilium Business Consulting Limited | Administrative & support | 2003 |
| Consilocum Ltd | Health & social care | 2023 |
| Consol Suncenter (Franchise) Limited | Other services | 2005 |
| Consort Services Ltd | Construction | 2008 |
| Consortio Consulting Ltd | Professional & scientific | 2012 |
| Consortium Developments and Investments Ltd | Construction | 2026 |
| Conspedia Ltd | Information & communication | 2016 |
| Constant Supported Living Limited | Health & social care | 2024 |
| Constays Ltd | Hospitality | 2025 |
| Constellation Education Services Limited | Education | 2019 |
| Constellation Events Ltd | Professional & scientific | 2022 |
| Constellation Group Limited | Financial services | 2018 |
| Construct Creations Limited | Construction | 2024 |
| Construct Interiors Ltd | Construction | 2023 |
| Construct Solutions Limited | Professional & scientific | 2005 |
| Constructed Properties Limited | Construction | 2020 |
| Constructing Insight Limited | Information & communication | 2025 |
| Construction & Project Management Ltd | Construction | 2024 |
| Construction Advice & Legal Services Limited | Professional & scientific | 2013 |
| Construction Gateman Company Ltd | Construction | 2016 |
| Construction Management (Atlantic Heights) Limited | Real estate | 2020 |
| Construction Professionals Ltd | Professional & scientific | 2010 |
| Construction Strategies Limited | Professional & scientific | 2012 |
| Construction Technical Services Limited | Construction | 2007 |
| Construction With Nicole Ltd | Construction | 2025 |
| Constructive Ventures Holdings Ltd | Financial services | 2025 |
| Constructivist Ltd | Education | 2018 |
| CONSU8 Ltd | Transport & logistics | 2024 |
| Consul Creative Consultancy Ltd | Professional & scientific | 2017 |
| Consula UK Ltd | Administrative & support | 2020 |
| Consult Believe Ltd | Information & communication | 2010 |
| Consulta Financial Group Limited | Financial services | 2023 |
| Consultable Limited | Professional & scientific | 2015 |
| Consultancy Technology Limited | Information & communication | 1996 |
| Consultant to Business Limited | Information & communication | 2016 |
| Consultias Talent Limited | Administrative & support | 2021 |
| Consulting Branch Ltd | Professional & scientific | 2026 |
| Consulting by Nada Ltd | Professional & scientific | 2022 |
| Consulting Pathway Ltd | Professional & scientific | 2018 |
| Consultnhd Limited | Construction | 2024 |
| Consultqa Limited | Professional & scientific | 2018 |
| Consumer Intelligence Limited | Administrative & support | 2003 |
| Consumer Waste Records LP | | 2014 |
| Consurgo Studio Ltd | Other services | 2025 |
| Contact Health Limited | Health & social care | 2014 |
| Contactum Electrical Contractors Ltd | Construction | 2018 |
| Container Hire Services Limited | Administrative & support | 2007 |
| Contech UK Shotcrete Services Limited | Construction | 2018 |
| Contego Media Group Ltd | Arts & recreation | 2017 |
| Contego Media Ltd | Information & communication | 2013 |
| Contemporary Therapies Limited | Health & social care | 2019 |
| Contemporis Freehold Limited | Real estate | 2007 |
| Contemporis RTM Company Limited | Households | 2009 |
| Content Designers Ltd | Professional & scientific | 2019 |
| Content Koala Ltd | Information & communication | 2021 |
| Conticom-Ics Limited | Education | 1998 |
| Continair Immigration Solutions Ltd | Professional & scientific | 2026 |
| Continair Ltd | Transport & logistics | 2022 |
| Continental Resources UK Limited | Wholesale & retail | 2018 |
| Continental Shop Limited | Wholesale & retail | 2014 |