| Carroll's Holdings Limited | Financial services | 2023 |
| Carrot.Co.Uk Limited | Information & communication | 1997 |
| Carry Overseas Ltd | Other services | 2015 |
| Carta Europe Administrator Limited | Financial services | 2023 |
| Carta Law Holdings Limited | Financial services | 2025 |
| Carta Law Limited | Extraterritorial | 2026 |
| Carter & Bailey Limited | Arts & recreation | 1962 |
| Carty Planning Solutions Ltd | Construction | 2020 |
| Casa 1910 AG LLP | | 2021 |
| Casa Property Development Limited | Extraterritorial | 2007 |
| Casa Vista Alta Ltd. | Real estate | 1976 |
| Case Renditions Ltd | Professional & scientific | 2025 |
| Case Surveying Limited | Professional & scientific | 2014 |
| Casey and Cowe Ltd | Wholesale & retail | 2020 |
| Cash Clarity Limited | Professional & scientific | 2024 |
| Cashel Building and Services Limited | Construction | 2022 |
| Caslon Limited | Wholesale & retail | 1936 |
| Caspar Curtis Consulting Limited | Information & communication | 2025 |
| Casparij Limited | Professional & scientific | 2025 |
| Cass PR Ltd | Professional & scientific | 2026 |
| Cassidy & Tate Limited | Real estate | 2011 |
| Cast Living Limited | Professional & scientific | 2021 |
| Casting Callback Ltd | Administrative & support | 2022 |
| Castle Rise Land Limited | Construction | 2011 |
| Castle Toys Ltd. | Real estate | 2015 |
| Castlehurst Consultants Limited | Construction | 2018 |
| Castro Construction Services Ltd | Construction | 2024 |
| Catalyst Sales and Marketing Limited | Professional & scientific | 2018 |
| Catapult Marketing Solutions Ltd | Administrative & support | 2024 |
| Category One Limited | Arts & recreation | 2007 |
| Cathean Limited | Administrative & support | 2004 |
| Cathedra Consulting Ltd | Professional & scientific | 2024 |
| Catheia Limited | Information & communication | 2011 |
| Catherine & LAM Ltd | Hospitality | 2026 |
| Cathquad Holdings Limited | Real estate | 2021 |
| Cathquad Properties Limited | Real estate | 1992 |
| Cato Motors Limited | Wholesale & retail | 2025 |
| Catrin Consulting Ltd. | Professional & scientific | 2016 |
| Cattle's Specialist Woodwork Ltd | Administrative & support | 2017 |
| Catton Estates Limited | Construction | 2017 |
| Catuaro Ltd | Professional & scientific | 2020 |
| Causality.It Limited | Information & communication | 2018 |
| Cavendish Pension Trustees Limited | Administrative & support | 1998 |
| Cavendish Search Limited | Administrative & support | 2016 |
| Cawglen Limited | Real estate | 1977 |
| Cawr Limited | Administrative & support | 2008 |
| Caxton Storage Ltd | Real estate | 2021 |
| Caztre Limited | Professional & scientific | 2025 |
| CB Printforce UK Limited | Manufacturing | 2018 |
| CB Trades Limited | Manufacturing | 2019 |
| CBE Design Limited | Professional & scientific | 2024 |
| Cbhawkins Ltd | Other services | 2021 |
| CC Comms Ltd | Professional & scientific | 2025 |
| CC Muntean Ltd | Transport & logistics | 2016 |
| Ccjn Homes Ltd. | Real estate | 2017 |
| CCM Affiliate Limited | Professional & scientific | 2024 |
| Ccsl Business Solutions Limited | Professional & scientific | 2000 |
| CDI DEV Ltd | Information & communication | 2026 |
| CDS Renovations Limited | Construction | 2014 |
| Cdsj Products Ltd | Manufacturing | 2021 |
| Cedar Construction (CC) Limited | Construction | 2019 |
| Cedar Realty Ltd | Real estate | 2024 |
| Cellar Door Pubs Limited | Hospitality | 2010 |
| Cellbarns Convenience Store Ltd | Wholesale & retail | 2025 |
| Celso CIC | Administrative & support | 2024 |
| Cennismotion Ltd. | Information & communication | 2017 |
| Censura Consulting Limited | Administrative & support | 2001 |
| Centaur Build Ltd | Construction | 2017 |
| Central Accounts Limited | Professional & scientific | 2014 |
| Central Valuation Network Services Ltd | Real estate | 2012 |
| Centred Mums Ltd | Other services | 2018 |
| Centurion Running Limited | Administrative & support | 2010 |
| Centy Ltd | Health & social care | 2011 |
| Ceraluna Health Ltd | Information & communication | 2025 |
| Ceramica Blue Limited | Extraterritorial | 2002 |
| Cersco Limited | Wholesale & retail | 2018 |
| Certs Assured Holdings Limited | Professional & scientific | 2015 |
| Certs Assured Limited | Manufacturing | 2012 |
| CES ST Albans Limited | Construction | 2012 |
| Cessta Contractors Ltd | Construction | 2016 |
| Ceto Energy Limited | Professional & scientific | 2023 |
| Ceylon Monarchy Ltd | Real estate | 2022 |
| CFM Holdings Limited | Financial services | 2016 |
| CFW Property Investments Ltd | Real estate | 2025 |
| CG Imports & Parts Limited | Wholesale & retail | 2017 |
| Cgmp Consultants Limited | Administrative & support | 2007 |
| Cgskin Limited | Professional & scientific | 2012 |
| CH Fire Safety Experts Limited | Administrative & support | 2019 |
| CHA and Nasta Ltd | Hospitality | 2022 |
| Chadcon Group Ltd | Construction | 2024 |
| Chader ALO Ltd | Hospitality | 2024 |
| Chaiz MCC SPV1 LLP | | 2024 |
| Chalfont Doors & Carpentry Services Limited | Administrative & support | 2010 |
| Chalfont Place (ST. Albans) Limited | Households | 2016 |
| Chalfont Storage Limited | Administrative & support | 2003 |
| Chalgrave Plumbing & Heating Ltd | Construction | 2012 |
| Challenge Sport and Education Ltd | Education | 2012 |
| Chamberlain Bennett & Sons Limited | Construction | 2018 |
| Chambers Beverages Ltd | Manufacturing | 2020 |
| Chambersole Limited | Wholesale & retail | 2023 |