| Compliance Cubed Limited | Professional & scientific | 2013 |
| Complita UK Limited | Professional & scientific | 2008 |
| Compound Capital Holdings Ltd | Real estate | 2026 |
| Compound Holdings Limited | Real estate | 2023 |
| Compunet Limited | Administrative & support | 2015 |
| Conacc Logistics Ltd. | Construction | 2014 |
| Conelco Ltd | Other services | 2020 |
| Coni Care Ltd | Health & social care | 2022 |
| Connaître Ltd | Other services | 2021 |
| Connect Care Recruit Ltd | Administrative & support | 2023 |
| Connect European Ltd | Education | 2026 |
| Connect Tech Global Limited | Information & communication | 2024 |
| Connectfunctionstudios Ltd | Information & communication | 2023 |
| Connexion (Rainham) Management Company Limited | Households | 2005 |
| Consilium Roofing Company Ltd | Construction | 2024 |
| Constantin 1960 Ltd | Transport & logistics | 2024 |
| Constat Solutions Ltd | Information & communication | 2007 |
| Construction & Railway Courses Ltd | Education | 2020 |
| Constructplus Ltd | Administrative & support | 2015 |
| Consularis Limited | Administrative & support | 2025 |
| Consultancy Jargon Free Limited | Professional & scientific | 2020 |
| Consultrixing Limited | Professional & scientific | 2015 |
| Consy & Brands Limited | Wholesale & retail | 2023 |
| Contav Limited | Transport & logistics | 2014 |
| Contemporary Renovations London Ltd | Construction | 2018 |
| Context Media Ltd | Information & communication | 2025 |
| Continental Seafood MK Ltd | Wholesale & retail | 2025 |
| Continuum Consultancy Ltd | Health & social care | 2026 |
| Contour Integral AI Labs Limited | Professional & scientific | 2026 |
| Cool and Beautiful Nightwear LLP | | 2006 |
| Cooper & Partner Ltd | Wholesale & retail | 2013 |
| Cooper Harland Limited | Professional & scientific | 2014 |
| Coore Ltd | Professional & scientific | 2019 |
| Coote Services (UK) Limited | Construction | 2012 |
| Copdock Car Wash Ltd | Other services | 2023 |
| Coral Communications Limited | Administrative & support | 2005 |
| Corby Lodge Letting Limited | Real estate | 2017 |
| Core Advisory Services Ltd | Other services | 2026 |
| Corimint Limited | Hospitality | 2025 |
| Corinthians Health Personnel Ltd | Administrative & support | 2012 |
| Cornelia Support Limited | Administrative & support | 2009 |
| Cornerstone Christian Leadership Centre | Other services | 2008 |
| Cornerstone Podiatry Clinic Ltd | Health & social care | 2026 |
| Cornerstone Recruitment Agency Ltd | Administrative & support | 2021 |
| Corvista Group Ltd | Professional & scientific | 2026 |
| Cosco Shipholdings (UK) Limited | Transport & logistics | 2008 |
| Cosco Shipping (UK) Company Limited | Transport & logistics | 1988 |
| Cosco Shipping Lines (UK) Limited | Transport & logistics | 1995 |
| Cosco Shipping Tanker (UK) Company Limited | Administrative & support | 2016 |
| Cosjon Ltd | Transport & logistics | 2025 |
| Cosmic UK Export and Import Services Ltd | Wholesale & retail | 2025 |
| Cosro Group Limited | Construction | 2014 |
| Cosro Holdings Limited | Financial services | 2026 |
| Cossy BD Ltd | Real estate | 2025 |
| Cotivra Ltd | Wholesale & retail | 2026 |
| Cotton Candy Crèche Limited | Health & social care | 2025 |
| Cotton Creations Limited | Wholesale & retail | 2020 |
| Couleur Cafe (UK) Limited | Hospitality | 2013 |
| County Brits Cleaning Services Limited | Administrative & support | 2017 |
| Couture & Comfort Limited | Manufacturing | 2025 |
| Covex Ltd | Construction | 2023 |
| Cowboys in Sweden Ltd | Information & communication | 2015 |
| CPD Skills Academy Ltd | Education | 2014 |
| Crack Deal Limited | Wholesale & retail | 2019 |
| Craftex Ltd | Construction | 2016 |
| Crayford Investment Ltd | Real estate | 2020 |
| Crayford Properties Ltd | Real estate | 2023 |
| Crazy COW LDN Ltd | Hospitality | 2025 |
| Crazy Source Ltd | Wholesale & retail | 2025 |
| CRB Waste Clearance Ltd | Water & waste | 2021 |
| Create Perfectly Ltd. | Manufacturing | 2020 |
| Created by Frazer Ltd | Professional & scientific | 2026 |
| Creating Life CIC | Professional & scientific | 2026 |
| Creative Accounts Ltd | Professional & scientific | 2012 |
| Creative Juices Limited | Information & communication | 1996 |
| Creative Mind Solutions Limited | Information & communication | 2023 |
| Creative Skills Ltd | Education | 2020 |
| Creative Solutions (London) Ltd | Construction | 2021 |
| Creative Value Sales Ltd | Wholesale & retail | 2023 |
| Creative Wellness Ltd | Health & social care | 2017 |
| Creative Wellness Wonder | Other services | 2019 |
| Credent Care Ltd | Health & social care | 2023 |
| Credent Solutions Ltd | Administrative & support | 2024 |
| Crescent Auto Group Limited | Wholesale & retail | 2026 |
| Crescent Build & Invest Ltd | Construction | 2017 |
| Crescent Systems Limited | Information & communication | 2009 |
| Crestcruze Ltd | Information & communication | 2024 |
| Crestqa Limited | Information & communication | 2009 |
| Crispy Krumble Ltd | Manufacturing | 2025 |
| Criss Cross Shutters Ltd | Construction | 2024 |
| Cristi Ltd | Transport & logistics | 2024 |
| Cristian Roofing Ltd | Construction | 2023 |
| Cristina's FAR From Home Ltd | Hospitality | 2019 |
| Cristina's Kitchen Ltd | Hospitality | 2017 |
| Cristina's Steak Ltd | Hospitality | 2012 |
| Critical Epos Solutions Ltd | Wholesale & retail | 2009 |
| Cromwell Property Assets Limited | Real estate | 2026 |
| Crown Auto Hub Limited | Wholesale & retail | 2019 |
| Crown Cash & Carry Ltd | Wholesale & retail | 2012 |
| Crown Cutz Ltd | Other services | 2025 |