| Construct MA Limited | Construction | 2025 |
| Construction Assessment Centre Limited | Construction | 2005 |
| Construction Awards Ltd | Education | 2020 |
| Construction Building Ltd | Construction | 2017 |
| Construction Disputes Limited | Professional & scientific | 2025 |
| Construction Skills Group Limited | Education | 2018 |
| Construction Steam Cleaning Services Ltd | Administrative & support | 2020 |
| CONSTRUCTION42 Limited | Construction | 2008 |
| Consturction Safety Consultants Ltd | Professional & scientific | 2022 |
| Consult IC Ltd | Professional & scientific | 2025 |
| Consultant Clinic Aesthetics Limited | Health & social care | 2013 |
| Consultant Clinic Holdings Limited | Financial services | 2017 |
| Consulting Team Ltd | Professional & scientific | 2025 |
| Contact Packaging Holdings Ltd | Administrative & support | 2018 |
| Contact Packaging Limited | Wholesale & retail | 1987 |
| Contact Physiotherapy Limited | Health & social care | 2009 |
| Contact Renewables and Solar Ltd | Energy | 2022 |
| Contact Solar Ltd | Construction | 2014 |
| Contact Union Accounting Ltd | Wholesale & retail | 2011 |
| Container Handling and Distribution Centre Ltd | Transport & logistics | 2024 |
| Contemporary PUB & Inns Ltd | Hospitality | 2025 |
| Content Colin Ltd | Information & communication | 2023 |
| Content Fellas Ltd | Professional & scientific | 2025 |
| Contentopia Ltd | Administrative & support | 2020 |
| Contract Ecology Limited | Administrative & support | 2010 |
| Contract Finishers Limited | Wholesale & retail | 1991 |
| Contract Hire Limited | Extraterritorial | 2004 |
| Contract Kitchen Consultants Ltd | Professional & scientific | 2024 |
| Contract Works Ltd | Construction | 2025 |
| Contracthire.Com Ltd | Extraterritorial | 2009 |
| Contractor's Slope Building Limited | Construction | 2021 |
| Contractx Limited | Information & communication | 2019 |
| Conuel Ltd | Wholesale & retail | 2021 |
| Convergent Group Solutions Ltd | Administrative & support | 2024 |
| Conveyor Belt Specialist Ltd | Manufacturing | 2019 |
| Convincemeaudio Limited | Information & communication | 2024 |
| Conway Court (Hoghton) Management Company Limited | Households | 2006 |
| COO PON Ltd | Administrative & support | 2007 |
| Cookie's Counselling Ltd | Health & social care | 2023 |
| Cooksworth Developments Limited | Construction | 2022 |
| Cool Campers NW Ltd | Wholesale & retail | 2025 |
| Cool Canvas Ltd | Extraterritorial | 2011 |
| Cool Solutions Air Conditioning Ltd | Construction | 2022 |
| Coolbreeze AC Ltd | Energy | 2007 |
| Coolcran Civils Ltd | Construction | 2022 |
| Coolfix Ltd | Construction | 2011 |
| Cooli Ltd | Manufacturing | 2026 |
| Coolmas Ltd | Financial services | 2020 |
| Coolwell Limited | Professional & scientific | 2002 |
| Coop Equipment Limited | Wholesale & retail | 2025 |
| Cooper and Gardiner Ltd | Professional & scientific | 2023 |
| Cooper Enviro Enterprises Limited | Professional & scientific | 2017 |
| Cooper Livestock Enterprises Ltd | Agriculture & fishing | 1978 |
| Cooper Lloyd Davies Limited | Extraterritorial | 1999 |
| Coopers of Ramsbottom Limited | Wholesale & retail | 2019 |
| Cooperwood Construction Ltd | Construction | 2019 |
| Coote Lane Garage Limited | Wholesale & retail | 2014 |
| Cootes Couriers Ltd | Transport & logistics | 2026 |
| COP Lane Garage Limited | Wholesale & retail | 2006 |
| Cope-Plus Medical Services Ltd | Health & social care | 2021 |
| Coppice Farm LLP | | 2013 |
| Coppice Publishing UK Ltd | Professional & scientific | 2013 |
| Copse Brook Leisure Limited | Hospitality | 2012 |
| Corax Consulting Limited | Professional & scientific | 2003 |
| Cords Education Limited | Public administration | 2022 |
| Core Comps Ltd | Arts & recreation | 2024 |
| Core Groundworks (NW) Ltd | Construction | 2024 |
| Core Media Productions Ltd | Information & communication | 2013 |
| Core Teachers Limited | Administrative & support | 2018 |
| Coremovers Ltd | Transport & logistics | 2025 |
| Coreplay Padel Ltd | Wholesale & retail | 2026 |
| Corevision Management Consultancy Ltd | Professional & scientific | 2025 |
| Corex Limited | Construction | 2025 |
| CORIUM3 Limited | Administrative & support | 2022 |
| Cornall's Garage Limited | Transport & logistics | 1984 |
| Corner Garage (Warton) Limited | Wholesale & retail | 2023 |
| Corner Stone Building & Maintenance Limited | Construction | 2009 |
| Corner Store Mini Market Limited | Wholesale & retail | 2025 |
| Cornerstone (DB) Group Limited | Construction | 2023 |
| Cornerstone Energy Group Ltd | Construction | 2026 |
| Cornerstone Fitout Limited | Construction | 2025 |
| Cornerstone Golf Advisory Limited | Extraterritorial | 2011 |
| Cornerstone Golf Limited | Professional & scientific | 2009 |
| Cornwell Engineering Solutions Limited | Professional & scientific | 2016 |
| Corona Contracts Ltd | Manufacturing | 2009 |
| Corona Holdings Limited | Wholesale & retail | 2017 |
| Corporate Clinic Energy UK Ltd | Wholesale & retail | 2020 |
| Corporate Clinic Ltd | Other services | 2019 |
| Corporate Commentary Ltd | Other services | 2011 |
| Corporate Helicopter Solutions Limited | Transport & logistics | 2014 |
| Corporate Wellness Solutions Limited | Health & social care | 2024 |
| Corrective Action Safety Ltd | Hospitality | 2022 |
| Cortez Recruitment Group Limited | Administrative & support | 2024 |
| Corton Beach (Blackpool) Ltd | Wholesale & retail | 2004 |
| Cortus Corporate Advisory Limited | Administrative & support | 2024 |
| Cortus Corporate Finance Limited | Administrative & support | 2024 |
| Cortus Transaction Services Limited | Administrative & support | 2024 |
| Corwar Ltd | Real estate | 2019 |
| Corwell Transport Limited | Transport & logistics | 2022 |
| COS 4 YOU Limited | Administrative & support | 2021 |