| Corinity Ltd | Financial services | 2024 |
| Corlink Ltd | Information & communication | 2025 |
| Cornerstone.F. London Limited | Construction | 2024 |
| Cornwell Investments Ltd | Real estate | 2025 |
| Corporate Capability Ltd | Professional & scientific | 2012 |
| Corporate Research Associates Ltd | Professional & scientific | 1997 |
| Corsair Components Limited | Information & communication | 2010 |
| Corsair International Holding Company Limited | Financial services | 2008 |
| Coruscant Property Ltd | Real estate | 2023 |
| Cosmosys Ltd | Information & communication | 2020 |
| Cost Insights Limited | Professional & scientific | 2017 |
| Costain Consulting Ltd | Professional & scientific | 2014 |
| Coteq Solutions Ltd | Professional & scientific | 2017 |
| Counselling Psychology Practice Limited | Health & social care | 2019 |
| Counselling Psychology Solutions Ltd | Health & social care | 2014 |
| Country DRY Cleaners (Berkshire) Ltd | Other services | 2011 |
| Countryside Nurseries (UK) Limited | Health & social care | 1996 |
| Countryside Nurseries LLP | | 2011 |
| Court Gardens Management Company (Goring-On-Thames) Limited | Households | 1998 |
| Court Gardens Residents Association Limited | Households | 1979 |
| Cousins & Denton Electrical Limited | Construction | 2023 |
| Coutcom Limited | Wholesale & retail | 2017 |
| Couturell Ltd | Wholesale & retail | 2025 |
| Coveford Limited | Agriculture & fishing | 1995 |
| COX Construction Management Ltd | Professional & scientific | 2022 |
| COX Hollow Residents Limited | Real estate | 2004 |
| Coxton Consulting Ltd | Professional & scientific | 2023 |
| CP International Investments Ltd | Other services | 2022 |
| CPG Consulting Engineers Limited | Professional & scientific | 2013 |
| Cpif Bain Ltd | Real estate | 2020 |
| Cpil Limited | Wholesale & retail | 2020 |
| Cplus Ltd | Information & communication | 2012 |
| Crafted by Design Limited | Manufacturing | 2016 |
| Crafted Flooring Limited | Extraterritorial | 2018 |
| Cranleigh C (TW9) RTM Company Limited | Households | 2024 |
| Cray Consulting Ltd | Information & communication | 2022 |
| Create a Space Holdings Limited | Real estate | 2025 |
| Create! Crafting From the Heart C.I.C. | Education | 2024 |
| Creating Better Futures | Education | 2011 |
| Creation Hloua LLP | | 2025 |
| Creative Global Consulting LLP | | 2026 |
| Creative Living (Berkshire) Ltd | Construction | 2014 |
| Creative Reward Consultancy Limited | Professional & scientific | 2009 |
| Creative Solutions Space Ltd. | Information & communication | 2014 |
| Creative Work Solutions Ltd | Information & communication | 2024 |
| Creatus Consulting Limited | Information & communication | 2010 |
| Creonova Consulting Limited | Professional & scientific | 2012 |
| Crescentedge Brickwork Ltd | Construction | 2025 |
| Cressex Square Limited | Households | 2017 |
| Cresswell's Garage (Wokingham) Limited | Wholesale & retail | 1971 |
| Cresswells Property Ltd | Real estate | 2022 |
| Crest Meridian Limited | Wholesale & retail | 2011 |
| Crested Crane Management Ltd | Real estate | 2016 |
| Cricketers GIN Limited | Manufacturing | 2019 |
| Crimson Valley Limited | Hospitality | 2025 |
| Cristian Burtea Construction Ltd | Construction | 2017 |
| Critical Leap Limited | Professional & scientific | 2000 |
| Critical Steps Ltd | Education | 2023 |
| Crown House (Thatcham) Management Company Limited | Households | 2014 |
| Crownglobe Management Limited | Households | 1996 |
| Crowthorne Lodge (Block 1) RTM Company Limited | Households | 2025 |
| Crowthorne Lodge (Block 2) RTM Company Limited | Households | 2025 |
| Cruiser Business Solutions Ltd | Manufacturing | 2016 |
| Cruz Lighting Limited | Wholesale & retail | 2025 |
| Cryptologic Ltd | Manufacturing | 2019 |
| Crystal Clear Pictures Limited | Information & communication | 2025 |
| Crystal Quality Cleaning Limited | Administrative & support | 2014 |
| CSA Golf Limited | Arts & recreation | 2015 |
| CSA Partners Ltd | Administrative & support | 2020 |
| Csem Group Limited | Construction | 2018 |
| CSI Southeast Ltd | Construction | 2014 |
| CSI Surveys Ltd | Professional & scientific | 2023 |
| Cslj Wills Limited | Professional & scientific | 2012 |
| CSP Group Ltd | Professional & scientific | 2026 |
| Cspi Ltd | Information & communication | 1999 |
| CT Global Contracting Limited | Information & communication | 2026 |
| CTC Estates Ltd | Real estate | 2022 |
| CTC Tennis Limited | Other services | 2018 |
| Ctc-Investments Limited | Professional & scientific | 2020 |
| CTS Automotive Insights Limited | Information & communication | 2021 |
| CTS Group Limited | Information & communication | 1995 |
| CTS Holdings Ltd | Other services | 2019 |
| Cu-Force Ltd | Manufacturing | 2026 |
| Cult Hills London Ltd | Wholesale & retail | 2024 |
| Cultivate Global HR Ltd | Administrative & support | 2025 |
| Curavest Ltd | Professional & scientific | 2024 |
| Cure Medical Limited | Wholesale & retail | 2023 |
| Curious Cognition Limited | Professional & scientific | 2018 |
| Curly Films Limited | Professional & scientific | 2013 |
| Curzon Development Solutions Limited | Professional & scientific | 2005 |
| Custodian 360 Limited | Information & communication | 2017 |
| Custom Web Apps Ltd | Information & communication | 2009 |
| Customer Systems Limited | Information & communication | 1998 |
| Cutbush Lane Ltd | Construction | 2025 |
| Cuts and Culture Limited | Other services | 2024 |
| Cutty Sark Limited | Administrative & support | 2015 |
| CV Consultants Ltd | Professional & scientific | 2023 |
| CWG Home Improvements Limited | Construction | 2022 |
| CWS Carpentry and Construction Limited | Construction | 2021 |
| CXC Consulting Limited | Professional & scientific | 2013 |