| Concordia Discors Ltd | Information & communication | 2012 |
| Condor Design Group Limited | Professional & scientific | 2017 |
| Condors Nest Ltd | Real estate | 2023 |
| Coneygar Consulting Limited | Public administration | 2013 |
| Confex 22 Ltd | Financial services | 2022 |
| Confex Limited | Administrative & support | 1972 |
| Confluence Coaching Limited | Other services | 2018 |
| Congleton Crematorium Ltd | Other services | 2018 |
| Coniston Stonecraft 2020 Ltd | Manufacturing | 2020 |
| Connected Development Consulting Ltd | Professional & scientific | 2021 |
| Connie Trading Limited | Hospitality | 2014 |
| Connor and Co Limited | Professional & scientific | 2011 |
| Conquering Steps Limited | Administrative & support | 2021 |
| Conrad Gadd Barrister Ltd | Professional & scientific | 2020 |
| Consall Valley Sporting Club Limited | Arts & recreation | 2024 |
| Conscious Cotswolds Ltd | Other services | 2024 |
| Conscious Creation UN Limited | Wholesale & retail | 2024 |
| Conscious Vision SEO Ltd | Professional & scientific | 2023 |
| Consense Limited | Administrative & support | 2004 |
| Consiglio Consulting Ltd | Real estate | 2026 |
| Consilience Consulting Limited | Professional & scientific | 2011 |
| Consillium Limited | Professional & scientific | 2010 |
| Construction Brainbox Limited | Information & communication | 2017 |
| Construction Commercial Services Limited | Construction | 2022 |
| Construction Data Ltd | Information & communication | 2020 |
| Consulting Positions LLP | | 2003 |
| Consultus PM Limited | Information & communication | 2018 |
| Consumer Insight & Strategy Ltd | Professional & scientific | 2013 |
| Contemporary Glazing Solutions Ltd | Manufacturing | 2019 |
| Content Chef Ltd | Professional & scientific | 2021 |
| Contexium Ltd. | Information & communication | 2026 |
| Context Land Ltd | Professional & scientific | 2018 |
| Contextus Cleaning Ltd | Administrative & support | 2025 |
| Continental Computers Limited | Extraterritorial | 1996 |
| Continental Limited | Information & communication | 1983 |
| Continental Shareholders Limited | Information & communication | 2018 |
| Continuity Care Ltd | Health & social care | 2010 |
| Contour (UK) Limited | Wholesale & retail | 2007 |
| Contract Interior Systems Limited | Construction | 2020 |
| Contracts One Ltd. | Professional & scientific | 2010 |
| Contrast Security UK Limited | Administrative & support | 2018 |
| Contrast Wellness Ltd | Health & social care | 2024 |
| Controlplane Group Limited | Financial services | 2022 |
| Convergence Design Limited | Professional & scientific | 2020 |
| Converse Financial Limited | Financial services | 2026 |
| Converse Law Limited | Professional & scientific | 2014 |
| Convies Group Ltd | Agriculture & fishing | 2026 |
| Convies Ltd | Administrative & support | 2020 |
| Conviva Ltd | Information & communication | 2012 |
| Conway House Limited | Professional & scientific | 2023 |
| Cook Residential Lettings Limited | Real estate | 2018 |
| Cook Residential Limited | Real estate | 2012 |
| Cooking With Coops Limited | Hospitality | 2023 |
| Cool Planet Consulting Ltd | Professional & scientific | 2022 |
| Coombe Farm Wines Limited | Wholesale & retail | 2010 |
| Coombes Everitt Architects Ltd | Professional & scientific | 2013 |
| Coombeseveritt Properties Ltd | Real estate | 2023 |
| Cooper & TAN Investments Ltd | Real estate | 2018 |
| Cooper Mckenzie Stokes Limited | Professional & scientific | 2020 |
| Coordinated Active Lifestyle Management CIC | Health & social care | 2017 |
| Coote Consulting Limited | Professional & scientific | 2025 |
| Cooter's Carpentry and Decorating Ltd | Construction | 2013 |
| Copes Consulting Ltd | Professional & scientific | 2023 |
| Copper CRM (United Kingdom) Limited | Administrative & support | 2018 |
| Copper Lion Distillery Limited | Manufacturing | 2020 |
| Coppernose Ltd | Manufacturing | 2014 |
| Copperwood Construction Limited | Construction | 2003 |
| Coppice Gate (Management) Limited | Households | 1991 |
| Coppmed Limited | Health & social care | 2011 |
| Coproco Ltd | Real estate | 2025 |
| Copse Green Holdings Limited | Agriculture & fishing | 2015 |
| Copsegrove Developments Limited | Professional & scientific | 1991 |
| Cor-Gre Investments Ltd | Construction | 2002 |
| Coral Shipping UK Ltd | Transport & logistics | 2026 |
| Coral Tree Travel Ltd | Administrative & support | 2019 |
| Coralie Estrade Landscape & Garden Design Limited | Administrative & support | 2024 |
| Corbyn Sands (Torquay) Management Company Limited | Households | 2015 |
| Corcra Security Limited | Information & communication | 2022 |
| Cordas Consultancy Ltd | Professional & scientific | 2025 |
| Cordolium Holdings Ltd | Financial services | 2025 |
| Cordoneanu Ltd | Transport & logistics | 2025 |
| Core Asset Marketing Ltd | Professional & scientific | 2019 |
| Core Worx Apex Limited | Construction | 2023 |
| Core Worx Maintenance Limited | Other services | 2025 |
| Coredynamics Limited | Professional & scientific | 2009 |
| Coretech Security Holdings Limited | Financial services | 2022 |
| Coretech Security Services Limited | Financial services | 2020 |
| Corinium Cast Stone Limited | Manufacturing | 2014 |
| Corinium Life Science Advisors Ltd | Professional & scientific | 2026 |
| Corinne Povey Ltd | Administrative & support | 2015 |
| Corinthian IT Ltd | Information & communication | 2026 |
| Cornelian Limited | Professional & scientific | 2005 |
| Corner Coffee Co. Ltd | Hospitality | 2024 |
| Corner House Norwich LLP | | 2012 |
| Cornerhouse Hotel Limited | Hospitality | 1999 |
| Cornerstones (Cheltenham) Management Company Limited | Households | 1986 |
| Cornerstones Associates Limited | Financial services | 2016 |
| Cornus Consultancy Limited | Professional & scientific | 2005 |
| Cornwell Carpentry Solutions Ltd | Construction | 2021 |
| Cornwell Construction Homes Ltd | Construction | 2013 |