| Citywide Hire Limited | Wholesale & retail | 2021 |
| CJM Carpentry & Construction Ltd | Construction | 2021 |
| Cjpe Designs Ltd | Wholesale & retail | 2024 |
| Clarence Court Management Company (Hinckley) Limited | Households | 1988 |
| Clarence Hive Ltd | Hospitality | 2022 |
| Clark Jones Consultancy Limited | Professional & scientific | 2026 |
| Clarkeys Property Solutions Ltd | Real estate | 2023 |
| Clas Education Consultancy Limited | Education | 2024 |
| Classics & Chrome Ltd | Manufacturing | 2006 |
| Clay Electrical Ltd | Construction | 2023 |
| Click Meds Limited | Wholesale & retail | 2026 |
| Client Portal IO Ltd | Information & communication | 2024 |
| Clifford House Associates Limited | Professional & scientific | 2011 |
| Climbatize Ltd | Administrative & support | 2015 |
| Clinical Health Technologies Ltd. | Administrative & support | 2013 |
| Cllaudetrans Ltd | Transport & logistics | 2017 |
| CLX Software Ltd | Information & communication | 2012 |
| CN Allport Cruise Services Limited | Transport & logistics | 2024 |
| CNC Centre Ltd | Manufacturing | 2009 |
| CNC Logistics Ltd | Transport & logistics | 2021 |
| CNC Software Solutions Ltd | Information & communication | 2012 |
| Cnc-Right Services Limited | Manufacturing | 2014 |
| Coachconnect Ltd | Arts & recreation | 2024 |
| Cobweb Construction Limited | Construction | 2015 |
| Code Crazy Ltd | Education | 2023 |
| Codevelopyou Limited | Professional & scientific | 2020 |
| Coexlion Holdings Ltd | Financial services | 2025 |
| Coexlion Limited | Professional & scientific | 2021 |
| Colin Burton & SON Builders Limited | Construction | 2003 |
| Collins & Co Financial Planning Ltd | Financial services | 2021 |
| Colour Flex Labels Limited | Manufacturing | 2006 |
| Coltarn Consulting Limited | Professional & scientific | 2017 |
| Coltarn Limited | Professional & scientific | 2015 |
| Comber Civil Engineering Limited | Construction | 2016 |
| Comber Construction Services Ltd | Construction | 2021 |
| Comea Computer Limited | Information & communication | 2010 |
| COMM2016 Limited | Extraterritorial | 2016 |
| Commotex Holdings Limited | Financial services | 2017 |
| Commotex Limited | Energy | 2017 |
| Companio Ltd | Manufacturing | 2019 |
| Complete Biohazard & Trauma Cleaning Ltd | Water & waste | 2022 |
| Complete Obsolete Limited | Wholesale & retail | 2025 |
| Complete Pipeline Solutions (UK) Ltd | Professional & scientific | 2015 |
| Complete Trade Supplies Ltd | Wholesale & retail | 2024 |
| Complete Vehicle Accessories Ltd | Wholesale & retail | 2013 |
| Composure Makeup Ltd | Other services | 2022 |
| Computer Plaza Ltd | Other services | 2026 |
| Conference Care Limited | Administrative & support | 2001 |
| Conference Care Travel Services Limited | Administrative & support | 2025 |
| Connors Bakery Limited | Manufacturing | 2016 |
| Constantinos&Co Ltd | Transport & logistics | 2018 |
| Consultora Ltd | Professional & scientific | 2020 |
| Content AV Ltd | Administrative & support | 2023 |
| Contingent Staff Processes Limited | Professional & scientific | 2016 |
| Continuity Healthcare Services Ltd | Health & social care | 2014 |
| Cooke & Sons Limited | Transport & logistics | 2009 |
| Copper Beech Developments Ltd | Construction | 2021 |
| Copperhouse Events Ltd | Administrative & support | 2021 |
| Cord Enterprises Ltd | Wholesale & retail | 2025 |
| Cordee (Holdings) Limited | Financial services | 2002 |
| Cordee Group Limited | Financial services | 2017 |
| Cordee Limited | Wholesale & retail | 1999 |
| Core Logistics Services Limited | Wholesale & retail | 2024 |
| Core Reformer Pilates Limited | Arts & recreation | 2023 |
| Coreedge Consultancy Ltd | Professional & scientific | 2025 |
| Corner Cafe(Hinckley) Ltd | Hospitality | 2022 |
| Corporate Mergers Limited | Financial services | 2007 |
| Cosarnia (U.K.) Limited | Manufacturing | 1988 |
| Cotswold Estates Limited | Construction | 1986 |
| County Aggregates Solutions Limited | Construction | 2026 |
| Courtside Tennis Limited | Arts & recreation | 2015 |
| Covalent Insights Limited | Professional & scientific | 2024 |
| Coventry Heat Treatment Services Ltd | Manufacturing | 2017 |
| Coventry Road Stores Ltd | Wholesale & retail | 2022 |
| Cozmik Enterprises Limited | Extraterritorial | 2016 |
| CP Construction Surfacing and Paving Contractors Ltd | Extraterritorial | 2022 |
| Cpc-Driver Training Limited | Education | 2009 |
| CR Auto Spa & Detailing Ltd | Administrative & support | 2024 |
| Craft Beer Online Ltd | Wholesale & retail | 2023 |
| Crafty Piglets Ltd | Health & social care | 2025 |
| Crane Electronics Group Limited | Professional & scientific | 2000 |
| Crane Electronics Limited | Manufacturing | 1971 |
| Crane Group Holdings Ltd | Financial services | 2020 |
| Crane Trustee Limited | Extraterritorial | 2020 |
| Cranmere Properties Limited | Real estate | 2015 |
| Crazy Jane Ltd | Manufacturing | 2007 |
| Crccarter Solutions Limited | Administrative & support | 2025 |
| Cream on the Green Ltd | Hospitality | 2019 |
| Creative Collaboration Group Limited | Administrative & support | 2020 |
| Creative Fruit Ltd | Professional & scientific | 2011 |
| Creative Landscapes (Burbage) Ltd | Administrative & support | 2016 |
| Credas Care Ltd | Health & social care | 2026 |
| Cribadvisor Ltd | Information & communication | 2019 |
| Crislung Travel Ltd | Transport & logistics | 2022 |
| Critical Mass Architects Limited | Professional & scientific | 2004 |
| Crocker Holdings Limited | Financial services | 2017 |
| Croner Group Limited | Professional & scientific | 2013 |
| Cruise Lounge Limited | Administrative & support | 2008 |
| Crunchy Wave Ltd | Professional & scientific | 2011 |
| Crunchycode Games Ltd | Information & communication | 2023 |