| Conducting Business Limited | Extraterritorial | 2002 |
| Condy Care Ltd | Health & social care | 2020 |
| Conex Property Ltd | Real estate | 2017 |
| Confederation of English Business Limited | Other services | 2006 |
| Conflict Resolution Skills Training Limited | Education | 2017 |
| Connectgo Ltd | Information & communication | 2018 |
| Conners Systems Limited | Information & communication | 2015 |
| Connolly Brothers (Curriers) Ltd | Manufacturing | 2012 |
| Connor Developments (UK) LLP | | 2007 |
| Connor Investments (UK) LLP | | 2007 |
| Conorfinn Ltd | Professional & scientific | 2020 |
| Conradi Morrison & Co T W | | 1997 |
| Consign Consultancy Ltd | Financial services | 2023 |
| Consistency Partners Limited | Professional & scientific | 2018 |
| Construction Arena Ltd | Administrative & support | 2003 |
| Construction Design & Co-Ordination Ltd | Construction | 2024 |
| Construction Professionals HR & Recruitment Ltd | Administrative & support | 2024 |
| Consultum Limited | Real estate | 2008 |
| Consumer SIX Ltd | Transport & logistics | 2024 |
| Content Cptl Ltd | Information & communication | 2026 |
| Content Intelligence Media Limited | Professional & scientific | 2018 |
| Context Waypoint Limited | Education | 2026 |
| Continental Deli-Bakery Limited | Hospitality | 2010 |
| Contingency Recovery Associates Limited | Professional & scientific | 2018 |
| Contour Blue Limited | Construction | 2025 |
| Contour Contracting Limited | Construction | 2026 |
| Contour Facilities Management Limited | Administrative & support | 2026 |
| Contour Property Group Limited | Financial services | 2025 |
| Contour Property Management Limited | Construction | 2025 |
| Conversations on Love Ltd | Information & communication | 2019 |
| Conyer Lodge Limited | Real estate | 2016 |
| Cooks Corner Childcare LLP | | 2012 |
| Cool Air Direct Ltd | Construction | 2019 |
| Coolhand Productions Limited | Information & communication | 2010 |
| Coombe Edge Management Company Limited | Households | 2011 |
| Cooper & Sons Roofing & Property Services Limited | Administrative & support | 2020 |
| Cooperburnett LLP | | 2013 |
| Cooperlegend Limited | Health & social care | 2014 |
| Copiking Limited | | 1989 |
| Copper Matters Limited | Water & waste | 2025 |
| Copperfield Plumbing and Heating Ltd | Construction | 2020 |
| Copperfields Investments Limited | Other services | 2012 |
| Copthorne Limited | Professional & scientific | 2000 |
| Coquet Publications Ltd | Information & communication | 2023 |
| Corbet Communications Limited | Other services | 2015 |
| Cordint Ltd | Wholesale & retail | 2015 |
| Coreelement Financial Limited | Professional & scientific | 2023 |
| Corema 1 Ltd | Real estate | 2019 |
| Coresight 360 Ltd | Information & communication | 2025 |
| Cormongers Land Ltd | Real estate | 2024 |
| Corn Exchange (LP) Limited | Real estate | 2018 |
| Corn Exchange Workspace Ltd | Real estate | 2017 |
| Cornerstone Digital Solutions Ltd | Information & communication | 2020 |
| Corporate Linx Limited | Information & communication | 2009 |
| Corporate Transformation Services Ltd | Information & communication | 2017 |
| Corvantix Capital Ltd | Financial services | 2026 |
| Corvantix Limited | Information & communication | 2018 |
| Corvus Talent Ltd | Administrative & support | 2024 |
| Cosack House Limited | Households | 1990 |
| Count and Cradle Consulting Ltd | Information & communication | 2023 |
| Countrywise Repairs Limited | Households | 2012 |
| County Care Limited | Health & social care | 2015 |
| County Wireless Services Limited | Real estate | 1923 |
| Cournell Limited | Professional & scientific | 2014 |
| Course Resources Ltd | Public administration | 2026 |
| Court Cecil Limited | Households | 2021 |
| Court Garden (Tunbridge Wells) Limited | Households | 1961 |
| Court Lodge Advisory Limited | Professional & scientific | 2018 |
| Courtlands Associates Limited | Professional & scientific | 2014 |
| Covent Garden FM Limited | Information & communication | 2012 |
| Cowdrey's Residents Association Limited | Households | 2003 |
| Coysten and Coysten Limited | Health & social care | 2006 |
| CP Marketing Limited | Administrative & support | 2016 |
| CPH Groundworks Limited | Construction | 2014 |
| Craft'D BUS Limited | Education | 2023 |
| Craftodia UK Limited | Wholesale & retail | 2020 |
| Craigmore Accountancy Limited | Professional & scientific | 2016 |
| Craigmore Bookkeeping Limited | Professional & scientific | 2016 |
| Cranbourne Gardens (Crowborough) Management Company Limited | Households | 2014 |
| Cranbrook DIY Limited | Wholesale & retail | 2006 |
| Cranes Surveyors Ltd | Administrative & support | 2001 |
| Crazy Tyres Ltd | Extraterritorial | 2014 |
| Creact Limited | Information & communication | 2021 |
| Creamy Whirls Limited | Wholesale & retail | 2020 |
| Create Balance Limited | Professional & scientific | 2020 |
| Create Your Future Ltd | Education | 2022 |
| Create.Nspired Ltd | Professional & scientific | 2023 |
| Creative Co-Pilots Limited | Information & communication | 2018 |
| Creative Craft Ltd | Wholesale & retail | 2023 |
| Creative Craft Works Ltd | Arts & recreation | 2023 |
| Creative Designs Kitchens Limited | Administrative & support | 2018 |
| Creative Fusion Limited | Professional & scientific | 2026 |
| Creative Management Limited | Information & communication | 2008 |
| Creative Outline Limited | Information & communication | 2014 |
| Creatives Direct (2006) Limited | Professional & scientific | 2006 |
| Cres Consulting Ltd | Professional & scientific | 2025 |
| Crescenti Pohl Advisory UK Ltd | Information & communication | 2025 |
| Crespigny House Maintenance Company Limited | Real estate | 1992 |
| Crestala Fencing & Construction Co.Limited | Manufacturing | 1966 |
| Crestwood Capital Advisors Limited | Financial services | 2017 |