| Clayholes Limited | Professional & scientific | 2025 |
| Clean & Clear Mobile EAR WAX Removal Ltd | Health & social care | 2025 |
| Clean OUR Oceans Limited | Water & waste | 2018 |
| Clear 'N' Collect Ltd | Manufacturing | 2019 |
| Clear in Cloud Ltd | Financial services | 2014 |
| Clearview Management Limited | Professional & scientific | 2012 |
| Clisdan Consulting Ltd | Professional & scientific | 2025 |
| CLK Motors Ltd | Wholesale & retail | 2024 |
| Clockwork London Limited | Administrative & support | 2014 |
| Cloud Club Smartness Ltd. | Wholesale & retail | 2024 |
| Cloudberry Consultancy Limited | Professional & scientific | 2019 |
| Clough Stuff Studio Ltd | Professional & scientific | 2025 |
| Clubbingaway Limited | Wholesale & retail | 2012 |
| CMC Communications Limited | Information & communication | 1995 |
| Coached by Jodie Ltd | Arts & recreation | 2024 |
| Cocoa Ventures Ltd | Real estate | 2025 |
| Coeus IO Ltd | Information & communication | 2023 |
| Coffee A'More Limited | Wholesale & retail | 2004 |
| Cognimotion Robotics Ltd. | Wholesale & retail | 2011 |
| Cognitivum Ltd | Professional & scientific | 2023 |
| Collective Economy Ltd | Administrative & support | 2025 |
| Colleen Brady Accountancy Ltd | Professional & scientific | 2025 |
| Colonel Fogg Enterprises Limited | Wholesale & retail | 2014 |
| Comet Mobile Limited | Information & communication | 2021 |
| Comitti Boats UK Ltd | Wholesale & retail | 2019 |
| Commentary Charts Ltd | Wholesale & retail | 2020 |
| Commercial Glazing Limited | Construction | 2023 |
| Companies With Grace Limited | Other services | 2015 |
| Compares Anything Ltd | Information & communication | 2026 |
| Complectus Limited | Financial services | 2008 |
| Complete Clinic Supply Ltd | Wholesale & retail | 2024 |
| Complete Home Control Limited | Wholesale & retail | 2010 |
| Complete Home Group Limited | Wholesale & retail | 2019 |
| Complete Marketing Limited | Professional & scientific | 1995 |
| Concept Education Holdings Limited | Education | 2018 |
| Concept Education Limited | Education | 2016 |
| Concierge Clinicians Ltd | Health & social care | 2025 |
| Concord Pursuits Ltd | Other services | 2013 |
| Concrete Builders Ltd | Construction | 2022 |
| Conethameshomes Ltd | Real estate | 2026 |
| Connecting West Limited | Professional & scientific | 2016 |
| Connibel Ltd | Professional & scientific | 2010 |
| Consolidated Mining and Investments Ltd | Professional & scientific | 2010 |
| Consort Place Residents Limited | Households | 2002 |
| Consultyon Ltd | Professional & scientific | 2019 |
| Contour & Renew Aesthetics Ltd | Other services | 2025 |
| Contour Aesthetics Clinic Ltd | Health & social care | 2026 |
| Contruent Limited | Administrative & support | 2011 |
| Cook Real Estate Holdings Limited | Real estate | 2024 |
| Cool Brains Limited | Education | 2022 |
| Coopers Hill Properties Ltd | Construction | 2026 |
| Coopers Structural Limited | | 1960 |
| Coppersmith's Plumbing & Heating Ltd | Construction | 2026 |
| Coppid Hall (Warfield) Ltd | Real estate | 2017 |
| Cornaxis Limited | Professional & scientific | 2002 |
| Cornerstone Asset Holdings Limited | Professional & scientific | 2011 |
| Corporate EDU Partners Limited | Administrative & support | 2025 |
| Corporate Visions UK Limited | Professional & scientific | 2003 |
| Corporation Road Freehold Limited | Construction | 2021 |
| Corsham Commercial Centre Limited | Professional & scientific | 1989 |
| Cotswolds Wine Company Limited | Wholesale & retail | 2018 |
| Courtenay Place Ltd | Real estate | 2025 |
| Courtland Developments Limited | Administrative & support | 2008 |
| Courtleigh Manor Residents Association Limited | Real estate | 1968 |
| Courtways Ltd | Real estate | 2018 |
| Coworth Management Limited | Construction | 2018 |
| Cowrie Accounting Ltd | Professional & scientific | 2019 |
| CP Global Services Ltd | Real estate | 2024 |
| CP Tuition Ltd | Education | 2024 |
| Cqme Ltd | Wholesale & retail | 2021 |
| Craft Industries Ltd | Wholesale & retail | 2025 |
| Creative Flooring (Properties) Limited | Professional & scientific | 1998 |
| Creative Flooring Limited | Wholesale & retail | 1998 |
| Creative Keyboard Limited | Administrative & support | 2012 |
| Crednet Limited | Financial services | 2024 |
| Creed Construction Ltd | Other services | 2017 |
| Crey Limited | Information & communication | 2019 |
| Crispr Therapeutics Ltd | Professional & scientific | 2014 |
| Croft Garage Conversions Ltd | Construction | 2025 |
| Croft Homes Developments Limited | Construction | 2000 |
| Crombie Creative Ltd | Information & communication | 2018 |
| Crown Clearance and Property Maintenance Ltd | Construction | 2025 |
| Crown Stamps Ltd | Wholesale & retail | 2025 |
| Crown Water Limited | Manufacturing | 2015 |
| Cruciate Property Limited | Real estate | 2008 |
| Cryo Science Limited | Health & social care | 2017 |
| CSD Properties Ltd | Real estate | 2024 |
| Cssm Consultants Limited | Professional & scientific | 2019 |
| Cudd Bentley Consulting Limited | Administrative & support | 2005 |
| Cudd Bentley EOT Limited | Administrative & support | 2023 |
| Cudd Bentley Holdings Limited | Extraterritorial | 2017 |
| Cuppion Ltd | Administrative & support | 2024 |
| Cura Labs Ltd | Manufacturing | 2026 |
| Curaidh Limited | Other services | 2021 |
| Curaidh Properties Limited | Real estate | 2023 |
| Curated by D Properties Ltd | Hospitality | 2025 |
| Curly COW Design Limited | Arts & recreation | 2024 |
| Curly Wurly Cafe Limited | Hospitality | 2023 |
| Customernomics Limited | Real estate | 2011 |
| Cxplus Limited | Professional & scientific | 2007 |