| Complete Marketing Services Ltd | Professional & scientific | 2018 |
| Complete Remediation Solutions Limited | Water & waste | 2025 |
| Completemaths Ltd | Education | 2020 |
| Comptrade Limited | Construction | 1991 |
| Comqi Holdings Ltd | Financial services | 2007 |
| Concept Point UK Limited | Real estate | 2015 |
| Concierge Service Providers Limited | Other services | 2010 |
| Concrete Trade Solution Ltd | Financial services | 2020 |
| Congruent Learning Limited | Other services | 2022 |
| Connaught Design Limited | Construction | 2016 |
| Connect Brickwork Limited | Construction | 2018 |
| Connectx Services Ltd | Professional & scientific | 2024 |
| Connor K Scenics Limited | Construction | 2022 |
| Conrad Merrin Limited | Construction | 2004 |
| Conservatory Archives Ltd | Wholesale & retail | 2015 |
| Consolidated London Investments Ltd | Financial services | 2016 |
| Constable Healthcare Limited | Health & social care | 2021 |
| Constable Real Estate Ltd | Real estate | 2024 |
| Construction London Facilities Management Ltd | Construction | 2019 |
| Construction on Site Ltd | Construction | 2018 |
| Constructor HD Limited | Wholesale & retail | 2016 |
| Consulting Market Traders Limited | Education | 2015 |
| Contento Carpentry and Joinery Ltd | Financial services | 2018 |
| Context Graphics Limited | Information & communication | 2002 |
| Continental Compliance Solution Ltd | Professional & scientific | 2020 |
| Contractsr Ltd | Professional & scientific | 2019 |
| Cookie Maker Ltd | Information & communication | 2025 |
| Coolstream Limited | Construction | 1983 |
| Cooper Advisory Services Ltd | Financial services | 2016 |
| Copenhagen Services Limited | Professional & scientific | 2025 |
| Copford Limited | Administrative & support | 1998 |
| Copper Plumber Ltd | Construction | 2026 |
| Coppersun Dental Care Limited | Health & social care | 2009 |
| Coral Investment Holdings Ltd | Other services | 2023 |
| Corcovado Consultancy Limited | Information & communication | 2024 |
| Corde Construct Ltd | Construction | 2015 |
| Coreadviz Digital Finance Ltd | Professional & scientific | 2017 |
| Coreadviz Limited | Information & communication | 2014 |
| Corline Coatings Limited | Wholesale & retail | 1991 |
| Cormorant Capital Strategies Limited | Financial services | 2005 |
| Cornice Associates Limited | Professional & scientific | 2010 |
| Cornmill Property Ltd | Real estate | 2023 |
| Coronation (Export Import) Limited | Administrative & support | 1974 |
| Coronation Developments Limited | Construction | 1990 |
| Coronation Street Industrial Properties Limited | Construction | 1981 |
| Coroscoba Limited | Households | 2018 |
| Corporate Administration Limited | Extraterritorial | 2002 |
| Corporate Rentals Limited | Real estate | 2000 |
| Corringham Court Management Limited | Construction | 1986 |
| Cosi FAN Tutti Ltd | Wholesale & retail | 2023 |
| Cosmo Tech Innovations Ltd | Professional & scientific | 2023 |
| Costa Paving Ltd | Construction | 2019 |
| Costi Spedition Ltd | Transport & logistics | 2016 |
| Costin Concrete Pump Ltd | Administrative & support | 2020 |
| Cotlet Construct Ltd | Construction | 2023 |
| Cottsbury Limited | Wholesale & retail | 2017 |
| Cougar.Uk.Com Ltd. | Manufacturing | 2000 |
| Counsellor Tutor Ltd | Other services | 2015 |
| Country View Ltd | Construction | 2011 |
| County Estate Planning Ltd | Other services | 2009 |
| Courtens Mews Residents Company Limited | Households | 1989 |
| Covasa Toys Limited | Manufacturing | 2025 |
| Covent Garden Property Ltd | Real estate | 2022 |
| Coventry Court Management Company Limited | Real estate | 2005 |
| Cover Drive Investments LLP | | 2010 |
| Covercord Limited | Wholesale & retail | 1988 |
| Coys Advisory Consultants Ltd | Administrative & support | 2023 |
| Cozzzy Ltd | Extraterritorial | 2017 |
| CP Business Consultancy Limited | Administrative & support | 2015 |
| CP Energy (UK) Limited | Wholesale & retail | 2011 |
| CP Secretaries Limited | Extraterritorial | 2000 |
| Cpdas Global Ltd | Education | 2016 |
| CPM Assets Ltd | Financial services | 2025 |
| Cpmusic Limited | Professional & scientific | 2020 |
| CPR Properties Limited | Real estate | 2017 |
| CR8 Property Development (UK) Limited | Real estate | 2018 |
| Craft Hands Ltd | Administrative & support | 2022 |
| Craft Pegg Limited | Professional & scientific | 2003 |
| Crafted Designs Ltd | Construction | 2025 |
| Craig Jones Design Limited | Professional & scientific | 2003 |
| Craven Park Assets Ltd | Real estate | 2023 |
| Crawford Building Services Ltd | Construction | 2014 |
| Crawford Dean Wealth Management Ltd | Financial services | 2020 |
| Crazy Party Ltd | Wholesale & retail | 2025 |
| Creck 3 Limited | Real estate | 2022 |
| Creck Limited | Real estate | 2018 |
| Credentia Business Processes Private Limited | Professional & scientific | 2008 |
| Credentia Foods Limited | Wholesale & retail | 2014 |
| Creighton & SON Holdings Limited | Manufacturing | 2011 |
| Creighton & SON Limited | Manufacturing | 1971 |
| Crescive Consulting Ltd | Information & communication | 2010 |
| Crest Electrical Services Limited | Construction | 2008 |
| Crest Networks UK Ltd | Information & communication | 2022 |
| Crestmoore Property Limited | Real estate | 2016 |
| CRG Construction Services Limited | Construction | 2021 |
| Crispins Shoes Limited | Wholesale & retail | 2003 |
| Cristo Design Services Limited | Information & communication | 2019 |
| Crmsee Ltd | Administrative & support | 2012 |
| Cromwell Associates Ltd | Professional & scientific | 2025 |
| Cromwell Crescent Management Company Limited | Households | 1994 |