| Conscious Impact Ltd | Hospitality | 2021 |
| Consensus Workspace Ltd | Construction | 2018 |
| Consistent Solutions Limited | Professional & scientific | 2023 |
| Consort Place Residents Association Limited | Households | 1993 |
| Constantines Property (CP) Limited | Real estate | 2024 |
| Constellation Global Holdings Ltd | Financial services | 2025 |
| Constructforce Recruitment Ltd | Administrative & support | 2023 |
| Construction Elite Ltd | Construction | 2018 |
| Construtech Engineering Limited | Construction | 2017 |
| Consulate Green (Bramhall) Management Company Limited | Households | 2020 |
| Consult a DEV Limited | Information & communication | 2026 |
| CONSULT4IMPACT Ltd | Professional & scientific | 2025 |
| Consultancy 58 Limited | Professional & scientific | 2018 |
| Consultation Skills Limited | Education | 2024 |
| Consultc Limited | Professional & scientific | 2017 |
| Consulthood Ltd | Real estate | 2022 |
| Consumer Claims Helpline Ltd | Professional & scientific | 2026 |
| Consumer Claims Lawyers Ltd | Administrative & support | 2017 |
| Contact Joinery & Building Services Ltd | Construction | 2022 |
| Contemporary SIX Ltd | Other services | 2024 |
| Contis Group Limited | Administrative & support | 2008 |
| Contoure Shapewear Ltd | Wholesale & retail | 2026 |
| Contrasoft Ltd | Real estate | 2020 |
| Control Systems International (UK) Limited | Information & communication | 1996 |
| Controls Testing Equipment Limited | Wholesale & retail | 1983 |
| Contxt Analytics Limited | Professional & scientific | 2020 |
| Conveo.Ai UK Ltd | Information & communication | 2025 |
| Convergix Intermediate UK Holdings Limited | Professional & scientific | 2022 |
| Convergix UK Holdings Limited | Professional & scientific | 2022 |
| Convergix UK, Ltd. | Manufacturing | 2000 |
| Conviso Limited | Professional & scientific | 2003 |
| Conway Capital Limited | Financial services | 2025 |
| Cook (UK) Limited | Wholesale & retail | 1982 |
| Cool Shutters Limited | Other services | 2013 |
| Coolneat Property Management Limited | Real estate | 1998 |
| Copieux Limited | Professional & scientific | 2016 |
| Copley Mills Limited | Real estate | 2022 |
| Copper Beeches (High Legh) Management Company Limited | Households | 2016 |
| Coppertop Surgery Limited | Administrative & support | 2009 |
| Corby's Bespoke Gardening Ltd | Administrative & support | 2022 |
| Corcentric International Limited | Professional & scientific | 2020 |
| Corcentric Limited | Information & communication | 1999 |
| Core Change Consulting Limited | Administrative & support | 2025 |
| Core CNC Limited | Manufacturing | 2014 |
| Core Integration Limited | Professional & scientific | 2022 |
| Core Living Properties Ltd | Real estate | 2026 |
| Core Manufacturing Support Services Limited | Administrative & support | 2010 |
| Core Syntax Limited | Professional & scientific | 2018 |
| Corevision Technologies Ltd | Financial services | 2025 |
| Corevo Systems Limited | Professional & scientific | 2025 |
| Corilla Plastics (Bridgend) Limited | Manufacturing | 2009 |
| Corilla Plastics Group Limited | Administrative & support | 2007 |
| Corimis Limited | Information & communication | 2021 |
| Corinium Accident Management Ltd | Administrative & support | 2018 |
| Corinthian Tax Advisers Limited | Professional & scientific | 2014 |
| Corinthian Tax LLP | | 2011 |
| Corks Property Ltd | Real estate | 2025 |
| Corner Stone 2014 Limited | Administrative & support | 2014 |
| Corningstone Accommodation Ltd | Real estate | 2019 |
| Cornish Cottage Holidays Limited | Extraterritorial | 2003 |
| Cornish Place Residents Company Limited | Households | 1999 |
| Cornwall Holiday Cottages Limited | Extraterritorial | 2003 |
| Coroden Ltd | Real estate | 2000 |
| Coronation Gold Limited Partnership | | 2009 |
| Coronation III General Partner Limited | Professional & scientific | 2005 |
| Corpacq Finance Limited | Professional & scientific | 2013 |
| Corpacq Group Limited | Financial services | 2024 |
| Corpacq Holdings Limited | Professional & scientific | 2021 |
| Corpacq Limited | Professional & scientific | 2006 |
| Corpacq Midco Limited | Professional & scientific | 2024 |
| Corpacq Properties Limited | Real estate | 2012 |
| Corpenergi Ltd | Wholesale & retail | 2025 |
| Corpgreen Ltd | Energy | 2025 |
| Correia Consulting Limited | Professional & scientific | 2019 |
| Corrona UK Holdings Limited | Administrative & support | 2019 |
| Corrosion Consultancy Services Limited | Manufacturing | 2005 |
| Corrozone Ltd | Education | 2023 |
| Corus Technologies Limited | Professional & scientific | 2011 |
| Cosmedica Solutions Limited | Real estate | 2025 |
| Cosmetic Damage Repair Specialists UK Limited | Manufacturing | 2024 |
| Cosmetic Labs Ltd | Wholesale & retail | 2026 |
| Cosmetic Plus Wholesale Ltd | Administrative & support | 2013 |
| Cost Less Carpets Ltd | Construction | 2021 |
| Costa Fish & Chip Limited | Hospitality | 2016 |
| Costaeng Ltd | Professional & scientific | 2025 |
| Costella Consulting Limited | Professional & scientific | 2010 |
| Costello`S Electrical Contractors Limited | Extraterritorial | 2007 |
| Costhetix Limited | Information & communication | 2024 |
| Cotesi (UK) Limited | Agriculture & fishing | 1988 |
| Cothinks Limited | Information & communication | 2021 |
| Cotswold Meadows Mortgage Advice Limited | Financial services | 2022 |
| Cottage Holidays (Carlisle) Ltd | Extraterritorial | 2010 |
| Cotton Traders Group Finance Limited | Wholesale & retail | 2018 |
| Cotton Traders Group Holdings Limited | Wholesale & retail | 2018 |
| Cotton Traders Holdings Limited | Wholesale & retail | 1994 |
| Cotton Traders Limited | Wholesale & retail | 1987 |
| Couch Potato 2 Ltd | Hospitality | 2025 |
| Couer Ltd | Wholesale & retail | 2020 |
| Couette Ltd | Financial services | 2015 |
| Couldn'T Care Less Ltd | Financial services | 1971 |