| Coffee Ritual Co. Ltd | Manufacturing | 2025 |
| Cognition Coaching and Consulting Ltd | Professional & scientific | 2019 |
| Cognitive Neurology Limited | Health & social care | 2011 |
| Cognoscere Limited | Professional & scientific | 2019 |
| Coldborough Park Estate Limited | Extraterritorial | 2014 |
| Cole Marie Partners (Holdings) Limited | Professional & scientific | 2020 |
| Coles Properties Ltd | Real estate | 2021 |
| Colgate Consulting Ltd | Professional & scientific | 2021 |
| Collaborative Elements Ltd | Professional & scientific | 2007 |
| Collegiate Legal Limited | Professional & scientific | 2012 |
| Collegiate Securities PLC | Financial services | 1992 |
| Collendean Investments Limited | Real estate | 2013 |
| Collinson's Landscaping Limited | Administrative & support | 2016 |
| Collis Developments Limited | Construction | 2018 |
| Collyer Communications Ltd | Professional & scientific | 2025 |
| Colossus Associates (UK) Holdings Limited | Financial services | 2024 |
| Columbus Investments Ltd | Financial services | 2021 |
| Columbus Technologies Limited | Information & communication | 2017 |
| Colyer Commercial Consultant Surveyors Limited | Real estate | 2024 |
| Comet Scientific Limited | Professional & scientific | 1994 |
| Comlan Services Ltd | Information & communication | 2017 |
| Commercial BMS Ltd | Administrative & support | 1999 |
| Commercial Optimisation Ltd | Professional & scientific | 2017 |
| Compass Fire Safety Ltd | Public administration | 2026 |
| Compass Structures Ltd | Construction | 2018 |
| Competiva Consulting Limited | Professional & scientific | 2017 |
| Complete Doorset Solutions Limited | Manufacturing | 2016 |
| Complete Facility Solutions Limited | Administrative & support | 2009 |
| Complete Physiotherapy Sussex Limited | Health & social care | 2024 |
| Compliance Pathways Limited | Professional & scientific | 2010 |
| Complylex Limited | Information & communication | 2019 |
| Compton Place (Southwater) Management Company Limited | Households | 2017 |
| Comptons Brow Management Company Ltd | Households | 2011 |
| Comptons Brow Residents Association Limited | Households | 1997 |
| Comptons Tennis Club Limited | Arts & recreation | 2011 |
| Computer Audio Design Limited | Manufacturing | 2010 |
| Comtech Europe Limited | Administrative & support | 2002 |
| Concinnity Service Management Ltd | Information & communication | 2021 |
| Conclean Limited | Administrative & support | 2025 |
| Connect LNE Electrical Ltd | Construction | 2019 |
| Connect Studio Ltd | Manufacturing | 2026 |
| Connetiv Properties Ltd | Hospitality | 2024 |
| Conquer the Internet Ltd | Professional & scientific | 2024 |
| Consolidated Technologies Limited | Professional & scientific | 2015 |
| Construction Clients Leadership Group Ltd | Construction | 2017 |
| Construction Software Limited | Information & communication | 2023 |
| Consultent Ltd | Professional & scientific | 2017 |
| Consulting DY Ltd | Information & communication | 2018 |
| Contemporary Blind Company Limited | Wholesale & retail | 2015 |
| Content Media Limited | Administrative & support | 2005 |
| Content Streams Ltd | Information & communication | 2022 |
| Contract Solutions Limited | Professional & scientific | 2025 |
| Control Logic Systems Ltd | Professional & scientific | 2018 |
| Convenience Corner Brighton Ltd | Wholesale & retail | 2023 |
| Conversation Starter Project CIC | Health & social care | 2023 |
| Conversion Capital Ltd | Professional & scientific | 2026 |
| Cook Consulting and Technical Ltd | Construction | 2021 |
| Cooks Electrical Ltd | Construction | 2019 |
| Cool Marshes Limited | Professional & scientific | 2008 |
| Coolham Holdings Limited | Financial services | 2023 |
| Coolhurst Property Management Limited | Households | 1995 |
| Cooltera Limited | Professional & scientific | 2016 |
| Coombe Lane Homes Limited | Construction | 2021 |
| Cooper Russell Design Ltd | Construction | 2025 |
| Cooper Weston Electrical Contractors Limited | Construction | 2020 |
| Cooper Weston Group Ltd | Construction | 2012 |
| Cooper Weston Holdings Limited | Financial services | 2026 |
| Cooper Weston Payroll Services Ltd | Professional & scientific | 2017 |
| Coopers Lettings Middlesex Limited | Real estate | 1998 |
| Coopers Maidenhead Ltd | Real estate | 2022 |
| Coopers of London Limited | Real estate | 2009 |
| Cootes Farm Community Limited | Administrative & support | 2020 |
| Copenstick Limited | Professional & scientific | 2022 |
| Copperfield Manor Management Limited | Hospitality | 1994 |
| Copperplate Limited | Real estate | 1978 |
| Copse Residents Association Limited(The) | Households | 1983 |
| Copywrite That Limited | Professional & scientific | 2020 |
| Coral Energy Limited | Administrative & support | 2016 |
| Cordek Holdings Limited | Financial services | 2021 |
| Cordek Limited | Manufacturing | 1973 |
| Core (Richmond) Limited | Construction | 2011 |
| Core Commercial Interiors Limited | Professional & scientific | 2011 |
| Core Customer Consulting Ltd | Professional & scientific | 2022 |
| Core Investment & Acquisitions Limited | Construction | 2011 |
| Corfe Castle Tavern Limited | Hospitality | 2015 |
| Corinthian Consultancy Limited | Professional & scientific | 2010 |
| Corners Ltd | Information & communication | 1997 |
| Cornerstone Farm Ltd | Agriculture & fishing | 2025 |
| Cornerstone Industries Ltd | Professional & scientific | 2014 |
| Coronis (International) Limited | Financial services | 2007 |
| Cosgrove Professional Services Limited | Information & communication | 2025 |
| Cosmo Empire Limited | Real estate | 2003 |
| Cosy Corner Stays Ltd | Hospitality | 2025 |
| COT 2 TOT Limited | Wholesale & retail | 2009 |
| Cottesmore School Limited | Education | 1899 |
| Cottham Engineering Services Limited | Administrative & support | 2006 |
| Cotton Thompson Cole Limited | Professional & scientific | 2011 |
| Country Bars Ltd | Hospitality | 2018 |
| Country Living Gardens & Groundworks Limited | Construction | 2018 |
| County Boilers Limited | Other services | 2017 |