| Clarence Ardley Rental Limited | Real estate | 2022 |
| Class 1 Servies Limited | Transport & logistics | 2015 |
| Classic Sash Ltd | Construction | 2024 |
| Classicworx Limited | Extraterritorial | 2019 |
| Claualex Trans Ltd | Transport & logistics | 2021 |
| Claws Beauty Limited | Other services | 2016 |
| Claws Nail and Beauty Limited | Other services | 2013 |
| Clayton Hall Sand Company Limited | Professional & scientific | 1982 |
| Cleanline Creative Limited | Manufacturing | 2020 |
| Cleanme Service Ltd | Other services | 2018 |
| Clearfix Solutions Ltd | Water & waste | 2022 |
| Clee Ventures Ltd | Real estate | 2025 |
| Clews Recycling Ltd | Water & waste | 1999 |
| Clic Services Limited | Administrative & support | 2017 |
| Click & Kind Co. Ltd | Information & communication | 2025 |
| Clients Assistant Limited | Information & communication | 2019 |
| Clients Solution Associate Limited | Information & communication | 2011 |
| Clifton Aquatics & Reptiles Ltd | Wholesale & retail | 2024 |
| Clifton Asset Group Ltd | Professional & scientific | 2022 |
| Clifton Cruisers Limited | Transport & logistics | 2000 |
| Clifton Property Assets Ltd | Real estate | 2022 |
| Clifton Road Car Sales Ltd | Wholesale & retail | 2024 |
| Clifton Village Stores Limited | Wholesale & retail | 2012 |
| Clinical Property Limited | Real estate | 2017 |
| Cliveparker Limited | Professional & scientific | 2025 |
| Cloud Heavy Industries Limited | Information & communication | 2026 |
| Cloud Tech Services Limited | Information & communication | 2017 |
| Cloud Transformation Solutions Ltd | Information & communication | 2022 |
| Clouddaze Limited | Administrative & support | 2023 |
| Cloudhight Consulting Ltd | Information & communication | 2023 |
| Cloudmedium Ltd | Information & communication | 2021 |
| Cloudrunner Investments Limited | Real estate | 2016 |
| CLT Healthcare Consultancy Ltd | Professional & scientific | 2022 |
| Club Yoga Limited | Other services | 2024 |
| Clubbie Holdings Ltd | Financial services | 2020 |
| Clusker Risk Limited | Professional & scientific | 2023 |
| CLZ Tech Limited | Professional & scientific | 2025 |
| CM General Building Ltd | Construction | 2017 |
| CM Trans Ltd | Administrative & support | 2016 |
| CMC Transport UK Ltd | Transport & logistics | 2005 |
| CMD Mortgages Ltd | Financial services | 2025 |
| CMM Technologies Ltd | Professional & scientific | 2015 |
| CMS Office Interiors Ltd | Construction | 2009 |
| CNE Services Limited | Information & communication | 2018 |
| Cngn Health Ltd | Real estate | 2024 |
| Cnme Limited | Financial services | 2017 |
| Cnmt Ltd | Manufacturing | 2019 |
| Coach House Equities Ltd | Construction | 2022 |
| Coates Automotive Developments Limited | Manufacturing | 2006 |
| Cock Robin Residents Limited | Water & waste | 1994 |
| Coclouds Ltd | Information & communication | 2022 |
| Coco Logistics Ltd | Transport & logistics | 2022 |
| Cocozu Ltd | Wholesale & retail | 2025 |
| Code Blue Specialist Vehicles Limited | Wholesale & retail | 2016 |
| Codebay Solutions Limited | Information & communication | 2006 |
| Codesigma Ltd | Professional & scientific | 2023 |
| Codrean Ltd | Transport & logistics | 2016 |
| Codreanu Cladding Ltd | Construction | 2022 |
| Codreanu Transport Ltd | Transport & logistics | 2026 |
| Coffee Please Ltd | Hospitality | 2025 |
| Cofiicare Ltd | Health & social care | 2024 |
| Cognilite Limited | Information & communication | 2023 |
| Cogreil Consultancy Limited | Professional & scientific | 2026 |
| Cojs Construction Ltd | Construction | 2016 |
| COLAB-8 Consulting Ltd | Professional & scientific | 2021 |
| Cold Mountain Limited | Financial services | 2019 |
| Cole Bros Commercial Limited | Real estate | 2025 |
| Colecraft Widebeam Boats Limited | Manufacturing | 2013 |
| Coleopterus Limited | Professional & scientific | 1997 |
| Colesniuc Transport Limited | Transport & logistics | 2018 |
| Colin Green Consulting Limited | Health & social care | 2013 |
| Collectable Arts Limited | Wholesale & retail | 2021 |
| Collectnsave Limited | Wholesale & retail | 2018 |
| Colledge Caravan Storage & Services Ltd | Transport & logistics | 2024 |
| Colledge Tree & Landscape Ltd | Administrative & support | 2021 |
| Collinson Security Limited | Administrative & support | 2026 |
| Comau U.K. Limited | Professional & scientific | 1988 |
| Combi Marketing Limited | Wholesale & retail | 2005 |
| Comfy Hammocks Ltd | Extraterritorial | 2016 |
| Comfyhaus Limited | Wholesale & retail | 2025 |
| Comharbor Limited | Wholesale & retail | 2017 |
| Commandment Property Services (United Kingdom) Limited | Real estate | 2005 |
| Commercial Real Estate Developments Ltd | Construction | 2020 |
| Comms Confident Limited | Professional & scientific | 2012 |
| Communication Terminated Ltd | Wholesale & retail | 2021 |
| Compania Limited | Information & communication | 2018 |
| Competence Assurance Solutions Ltd. | Professional & scientific | 1997 |
| Complete Estate Agents (Coventry) LLP | | 2014 |
| Complete Hub Technologies Limited | Manufacturing | 2015 |
| Complete Management System Ltd | Professional & scientific | 2024 |
| Composite Garden Studios Ltd | Construction | 2024 |
| Computer Allied Services (Rugby) Limited | Information & communication | 2011 |
| Conceptworld Holdings Limited | Professional & scientific | 2013 |
| Conceptworld Limited | Professional & scientific | 2007 |
| Conceptworld R & D Limited | Professional & scientific | 2013 |
| Concinnity Consultancy & Research Ltd | Professional & scientific | 2014 |
| Concord Systems Limited | Information & communication | 1989 |
| Concordiax Limited | Information & communication | 2006 |
| Concrete Related Solutions Ltd | Construction | 2025 |
| Confido Services Ltd | Wholesale & retail | 2024 |