| Comedy Drops Ltd | Arts & recreation | 2019 |
| Comfort Zone Furniture Ltd | Wholesale & retail | 2024 |
| Commercial Estate Managment Services Ltd | Real estate | 2022 |
| Commercial Fleet Holdings Ltd | Financial services | 2018 |
| Commercial Jack Preston Ltd | Wholesale & retail | 2023 |
| Commercial Site Developments Limited | Construction | 2001 |
| Commit Digital Limited | Professional & scientific | 2018 |
| Common Services Limited | Information & communication | 2023 |
| Commonwealth Risk Management Company (Crmc) Ltd | Professional & scientific | 2025 |
| Community Connect C.I.C. | Administrative & support | 2018 |
| Community Education Adults Disabilities Community Interest Company | Education | 2019 |
| Companion Community Technologies CIC | Information & communication | 2025 |
| Compass Speech & Language Therapy Ltd | Health & social care | 2025 |
| Compass Universal Limited | Administrative & support | 2014 |
| Complete Appliance Solutions Ltd | Other services | 2018 |
| Complete Bathroom Solutions Ltd | Construction | 2021 |
| Complete Chiropractic Limited | Health & social care | 2014 |
| Complete Electrical and Firetech Limited | Construction | 2017 |
| Complete Plumbing & Property Limited | Construction | 2018 |
| Complete Safe House UK Ltd | Construction | 2017 |
| Complete Shutter Services Holdings Limited | Other services | 2015 |
| Complete Shutter Services Limited | Manufacturing | 1993 |
| Complex Adaptive Limited | Professional & scientific | 2019 |
| Compliance Support Services Limited | Professional & scientific | 2021 |
| Composite Fencing and Decking Supplies Limited Limited | Construction | 2023 |
| Composite Services Ltd | Professional & scientific | 2015 |
| Comzique Control Systems Limited | Professional & scientific | 1998 |
| Conellos Trading Ltd | Hospitality | 2026 |
| Confidential Information Destruction Limited | Water & waste | 2001 |
| Conisbrough Holdings Limited | Other services | 2021 |
| Conlan Business Advisory Ltd | Administrative & support | 2020 |
| Connaught Conservatory Roofs Ltd | Manufacturing | 2006 |
| Connect AF Pharma Ltd | Wholesale & retail | 2025 |
| Connect Evolve Limited | Real estate | 2018 |
| Connect Healthcare Rotherham CIC | Health & social care | 2017 |
| Connectcomm Limited | Information & communication | 2002 |
| Connected Data Solutions Ltd | Information & communication | 2015 |
| Connected Vehicle Solutions Ltd | Information & communication | 2024 |
| Connecting Communities Worldwide Limited | Professional & scientific | 2009 |
| Connection Recruitment (Healthcare) Limited | Health & social care | 2018 |
| Connection Recruitment Limited | Administrative & support | 2001 |
| Connole Construction Services Ltd | Professional & scientific | 2018 |
| Connor Property Investments Limited | Real estate | 2019 |
| Conquest Law Ltd | Professional & scientific | 2020 |
| Consilium Draughting Limited | Professional & scientific | 2015 |
| Consilium Management Services Limited | Information & communication | 2010 |
| Constantin & Co Ltd | Wholesale & retail | 2014 |
| Constantin Property Ltd | Real estate | 2021 |
| Construct Electrical Limited | Construction | 2021 |
| Construct the Books Ltd | Professional & scientific | 2023 |
| Constructech Solutions Ltd | Information & communication | 2024 |
| Consulting Brain Ltd | Information & communication | 2019 |
| Consulting Mind Ltd | Information & communication | 2022 |
| Consultplug Education Ltd | Education | 2023 |
| Contact Centre Consultants Ltd | Professional & scientific | 2023 |
| Container City Limited | Administrative & support | 2011 |
| Content Enhance Ltd | Information & communication | 2024 |
| Continental Gold Consulting Limited | Construction | 2021 |
| Continental Gold New Cleveland Club Limited | Construction | 2024 |
| Continental Gold Old Mill Limited | Construction | 2024 |
| Contour Aesthetics Limited | Administrative & support | 2011 |
| Contractor BHM Limited | Public administration | 2018 |
| Control Systems (UK) Ltd | Information & communication | 2013 |
| Cooden Construction Ltd | Construction | 2024 |
| Cook Brown Energy Ltd | Professional & scientific | 2017 |
| Cook-Oooz Ltd | Hospitality | 2022 |
| Cooke & Co Interiors Ltd | Construction | 2021 |
| Cooke Morris Ltd | Real estate | 2023 |
| Cooke Ohana Ltd | Real estate | 2019 |
| Cookers Imported Direct Limited | Wholesale & retail | 2017 |
| Coombe Accident Repair Holdings Ltd | Financial services | 2021 |
| Coombe Gate Limited | Professional & scientific | 2020 |
| Cooper and Kirk Property Limited | Real estate | 2017 |
| Cooper and Turner Distribution Limited | Manufacturing | 2013 |
| Coopers Autobody Repairs Limited | Wholesale & retail | 2020 |
| Copacetic Enterprises Limited | Information & communication | 2021 |
| Copenhagen Infrastructure Service Company Ltd | Professional & scientific | 2015 |
| Copiam Ltd | Information & communication | 2014 |
| Copperwork Limited | Professional & scientific | 2009 |
| Copyblaze Ltd | Information & communication | 2001 |
| Coral Transport Ltd | Transport & logistics | 2022 |
| Cordon Security Services Ltd | Administrative & support | 2023 |
| Core Drive Solutions Ltd | Real estate | 2024 |
| Corepatch Networks Ltd | Construction | 2026 |
| Coretech Engineering Solutions Ltd | Professional & scientific | 2026 |
| Corium B Limited | Wholesale & retail | 2007 |
| Corner Stone Urban Group Ltd | Households | 2025 |
| Cornerstone Medical Consultancy Limited | Health & social care | 2025 |
| Cornice Designs Ltd | Extraterritorial | 2014 |
| Corwin Consultancy Limited | Information & communication | 2019 |
| COS Telecom Ltd | Construction | 2025 |
| Cosmetic Automotive Repairs Limited | Wholesale & retail | 2016 |
| Cosmic Beauty Box Limited | Wholesale & retail | 2019 |
| Cosmic Boogaloo Limited | Other services | 2025 |
| Cosmin Burlacu Ltd | Transport & logistics | 2016 |
| Cosmo Health Ltd | Information & communication | 2015 |
| Costa Locum Services Limited | Professional & scientific | 2018 |
| Costinsrl Limited | Transport & logistics | 2017 |
| Cotask Ltd | Information & communication | 2023 |
| Cotton & Ridout Ltd | Real estate | 2021 |