| Code Bearclaws Ltd | Information & communication | 2022 |
| Codeword Music Limited | Arts & recreation | 2018 |
| Codice Lieve Ltd | Information & communication | 2020 |
| Coglateral.Ai Limited | Information & communication | 2024 |
| Coin Mining Central Ltd | Wholesale & retail | 2019 |
| Cola BOY Productions Ltd | Arts & recreation | 2023 |
| Cold Fries Limited | Information & communication | 2025 |
| Cole Mechanical Solutions Ltd | Construction | 2025 |
| Coles Yard Mews Management Company Ltd | Professional & scientific | 2001 |
| Colindale Pase Limited | Real estate | 2018 |
| Collateral Educational Enterprises Limited | Education | 2009 |
| Collective Thinking Ltd | Other services | 2026 |
| Collett Design Associates Ltd | Professional & scientific | 2018 |
| Collingwood RPC Limited | Real estate | 2018 |
| Collins Architectural Ironmongery Ltd | Construction | 2023 |
| Colore DIT Limited | Administrative & support | 2022 |
| Colson Studio Ltd | Professional & scientific | 2025 |
| Colts Cabs Limited | Transport & logistics | 1991 |
| Columbus Telecom Solutions Limited | Professional & scientific | 1998 |
| Comet Wallet Ltd | Wholesale & retail | 2025 |
| Comfy Drive Executive Ltd | Transport & logistics | 2025 |
| Commercial Freeholds & Investments Ltd | Construction | 2015 |
| Commercial Property & Land Limited | Professional & scientific | 2010 |
| Commprex Limited | Construction | 2014 |
| Commsmaster Ltd | Information & communication | 2015 |
| Communicate Mobile Limited | Information & communication | 2004 |
| Community Transport Club Ltd | Construction | 2020 |
| Compare Investments DOT Guru Limited | Administrative & support | 2013 |
| Compatible Limited | Construction | 2017 |
| Compleat Food Network Limited | Hospitality | 1999 |
| Complete Fleet Support Services LLP | | 2025 |
| Complete Property Finance Ltd. | Financial services | 2024 |
| Complex Spine Ltd | Health & social care | 2017 |
| Complex’S Clarity Health Group Limited | Public administration | 2025 |
| Compton Insurance Services and Media Ltd | Information & communication | 2002 |
| Computaform (UK) Limited | Wholesale & retail | 2008 |
| Computer & Music Services Limited | Information & communication | 2000 |
| Computer Security Technology Ltd. | Information & communication | 1997 |
| Comsurv Consultancy Limited | Professional & scientific | 2024 |
| Concept Caring Casa Limited | Real estate | 2023 |
| Concepto Diagnostics Limited | Health & social care | 2012 |
| Concierge Prive Ltd | Hospitality | 2025 |
| Conciergeandco Ltd | Wholesale & retail | 2019 |
| Concrete Harbor Limited | Extraterritorial | 2003 |
| Conditional Technologies Ltd | Information & communication | 2025 |
| Conduit CGR Ltd | Real estate | 2026 |
| Connatix UK Limited | Information & communication | 2020 |
| Connect Consortium Ltd | Construction | 2023 |
| Connect Consultancy Group (CCG) Limited | Professional & scientific | 2022 |
| Connecto Digital Limited | Financial services | 2025 |
| Connie Content Ltd | Information & communication | 2019 |
| Conquest Power Limited | Construction | 2025 |
| Conrad Advertising (North) Limited | Professional & scientific | 1996 |
| Conrad Advertising Limited | Professional & scientific | 2000 |
| Conscious Consultancy Services Limited | Other services | 2025 |
| Consortium Real Estate Limited | Real estate | 2006 |
| Construction Markets Limited | Professional & scientific | 2008 |
| Consultant Physicians Ltd | Health & social care | 2015 |
| Consulting Stream Technologies Limited | Other services | 2008 |
| Contact Therapy Ltd | Health & social care | 2012 |
| Contego Events Limited | Administrative & support | 2015 |
| Contemporary Industries and Commercial Supplies Limited | Health & social care | 2015 |
| Content Creative Media Ltd | Arts & recreation | 2017 |
| Contract Plant Services Limited | Manufacturing | 2014 |
| Converge Venues LLP | | 2025 |
| Convex Solutions Ltd | Professional & scientific | 2025 |
| Conway and Company Solicitors Limited | Administrative & support | 2013 |
| Cool GAS Air Conditioning Ltd | Construction | 2019 |
| Cool Heat GAS Ltd | Manufacturing | 2015 |
| Cool Jellybean Limited | Information & communication | 2017 |
| Cool Planners Limited | Administrative & support | 2013 |
| Cool Runway Limited | Information & communication | 2021 |
| Cool Sky Air Conditioning Ltd | Construction | 2023 |
| Cooley & Daughter LLP | | 2025 |
| Cooley & Sons LLP | | 2025 |
| Coolsand Studio Ltd | Wholesale & retail | 2025 |
| COOP3RFILMS Ltd | Information & communication | 2025 |
| Cooper White Group Ltd | Administrative & support | 2011 |
| Copier Installs Limited | Administrative & support | 2012 |
| Copper FOX Films Ltd | Information & communication | 2026 |
| Coral Ace Business Solutions INT Ltd | Information & communication | 2015 |
| Coral Living Ltd | Professional & scientific | 2019 |
| Cordially WED Limited | Information & communication | 2026 |
| Core Global Protection Ltd | Administrative & support | 2020 |
| Core Group London Limited | Professional & scientific | 2020 |
| Coreacc Limited | Professional & scientific | 2011 |
| Corndog Productions Limited | Information & communication | 2025 |
| Cornwall House Management Company (RTM) Limited | Professional & scientific | 2004 |
| Cornwall Inns Limited | Professional & scientific | 2015 |
| Cornwell Property Consultants Ltd | Real estate | 2018 |
| Corona Medical Ltd | Health & social care | 2018 |
| Corporate Legal Services Solutions Limited | Professional & scientific | 2024 |
| Corps Support Limited | Administrative & support | 2017 |
| Corrade Property Limited | Real estate | 2016 |
| Cortex Logic Ltd | Information & communication | 2019 |
| Cosa Nostra Music Ltd | Arts & recreation | 2015 |
| Cosmedcs Ltd | Health & social care | 2018 |
| Cosmic Violet Events Ltd | Administrative & support | 2024 |
| Costa Corporation Ltd | Construction | 2025 |
| Costache O Ltd | Transport & logistics | 2015 |