| Cotton Spring View Limited | Households | 2016 |
| Cottrell Property Management Ltd | Households | 2026 |
| Country Cover Limited | Real estate | 2008 |
| Country Guns Ltd | Wholesale & retail | 2026 |
| Couscous Ltd | Hospitality | 2022 |
| Couture Hair Ltd | Other services | 2012 |
| Covas Healthcare Limited | Professional & scientific | 2018 |
| Cowlgrove Limited | Construction | 1982 |
| CP Properties 4U Ltd | Real estate | 2022 |
| CPB Financial Management Limited | Professional & scientific | 2008 |
| Cqrs Limited | Professional & scientific | 2008 |
| CR Escapes Ltd | Administrative & support | 2025 |
| Craft & Cleaver Events Ltd | Hospitality | 2026 |
| Craftport Consulting Limited | Professional & scientific | 2013 |
| Crafty FOX London Ltd | Wholesale & retail | 2025 |
| Craig Huddleston Consultancy Limited | Health & social care | 2015 |
| Cranberry Local Ltd | Wholesale & retail | 2025 |
| Crank to COG Ltd | Manufacturing | 2020 |
| Crave Food Consultants Limited | Wholesale & retail | 2024 |
| CRB Catalyst Consulting Ltd | Information & communication | 2025 |
| Crd.Productions Ltd | Information & communication | 2022 |
| CRE Asset Management Limited | Financial services | 2018 |
| CRE8TIFY Limited | Professional & scientific | 2017 |
| CRE8TIVE Games Trading Limited | Wholesale & retail | 2025 |
| CRE8TIVE Resources CIC | Education | 2020 |
| Cream Marketing Solutions Limited | Administrative & support | 2009 |
| Create a Splash Limited | Arts & recreation | 2014 |
| Create Control Limited | Professional & scientific | 2018 |
| Create Outdoors Limited | Other services | 2003 |
| Createch Global Solutions Ltd | Wholesale & retail | 2020 |
| Creative Casa Ltd | Construction | 2020 |
| Creative Design Warehouse Limited | Information & communication | 2013 |
| Creative Developments (East Sheen) Limited | Construction | 2013 |
| Creative Project Management Ltd | Administrative & support | 2015 |
| Creativity & Sons Ltd | Professional & scientific | 2025 |
| Creova Group Ltd | Financial services | 2025 |
| Cresswell Electrical Ltd | Construction | 2022 |
| Crew Provisions Ltd | Manufacturing | 2024 |
| Crichton Partners Limited | Health & social care | 2014 |
| Cridra Holding Ltd | Information & communication | 2022 |
| Crimson Badger (UK) Limited | Manufacturing | 2023 |
| Crimson Interactive Limited | Professional & scientific | 2019 |
| Crisp Solutions Limited | Professional & scientific | 2005 |
| Criticalconsumables Ltd | Wholesale & retail | 2024 |
| Croft Farm Wheathampstead Limited | Hospitality | 1978 |
| Croftby Real Estate Limited | Professional & scientific | 2015 |
| Crossfields Properties Ltd | Construction | 2020 |
| Crouch Hall Lane Management Company Limited | Real estate | 2021 |
| Crouching Dragon Ltd | Hospitality | 2026 |
| Crowdfluence Ltd. | Professional & scientific | 2016 |
| Crowlink Holdings Limited | Extraterritorial | 2015 |
| Crown Brickwork and Scaffolding Ltd | Construction | 2019 |
| Crown Refining Limited | Administrative & support | 2010 |
| Crowne Construction Limited | Construction | 2003 |
| Crownedge UK Limited | Other services | 2022 |
| Crutches Ltd | Information & communication | 2021 |
| Cryptique Tax Ltd | Information & communication | 2026 |
| Crystal Apiary Ltd | Wholesale & retail | 2024 |
| Crystal Cleaning Agency Ltd | Administrative & support | 2009 |
| Crystal Property Improvements Limited | Other services | 2023 |
| CS2B Limited | Construction | 2017 |
| Csaki Construction Limited | Construction | 2023 |
| Csmc Coaching Ltd | Arts & recreation | 2021 |
| CTA Solutions Ltd | Real estate | 2019 |
| CTS Buildsafe Ltd | Information & communication | 2026 |
| Cube Italia Ltd | Wholesale & retail | 2023 |
| Cubi Properties (UK) Ltd | Real estate | 2025 |
| Culley Financial Advice Ltd | Financial services | 2025 |
| Cumberland Court (Freehold) Ltd | Real estate | 2000 |
| Curated Voyages Ltd | Administrative & support | 2025 |
| Curiosity & Clarity Ltd | Administrative & support | 2018 |
| Curly Dog Properties Limited | Real estate | 2001 |
| Curry Xpress Limited | Hospitality | 2025 |
| Custardo Ltd | Information & communication | 2020 |
| Custom Building and Services Ltd | Construction | 2022 |
| Custom Home Design Limited | Professional & scientific | 2012 |
| CUT CUE Limited | Information & communication | 2006 |
| Cute Property Limited | Real estate | 2022 |
| Cutenhoe (176) DCL Limited | Real estate | 2020 |
| Cutenhoe DCL Ltd | Real estate | 2016 |
| CUTENHOE(174) DCL Limited | Real estate | 2018 |
| CUTENHOE(178) DCL Limited | Real estate | 2018 |
| Cutie & Beauty Limited | Real estate | 2019 |
| Cvns Holdings Limited | Real estate | 2021 |
| CW Lettings Ltd | Real estate | 2023 |
| CWF Film Services Ltd | Arts & recreation | 2026 |
| CXO Global Limited | Professional & scientific | 2025 |
| CXO LAB Ltd | Administrative & support | 2023 |
| CXP Property Investments Limited | Real estate | 2020 |
| Cyber Kaizen Limited | Information & communication | 2024 |
| Cyberdirect Limited | Wholesale & retail | 2025 |
| Cyberdyn Security Limited | Information & communication | 2021 |
| Cyberpal Ltd | Administrative & support | 2017 |
| Cyberthinktest Ltd | Information & communication | 2024 |
| CYBTAM228 Ltd | Arts & recreation | 2024 |
| CYD Projects Limited | Professional & scientific | 2007 |
| Cygnus Talent Limited | Information & communication | 2025 |
| Cyknal Limited | Professional & scientific | 2008 |
| Cynozure Group Ltd | Information & communication | 2016 |
| Cyrus Home Care Ltd | Health & social care | 2023 |