| Commonside Investments Limited | Extraterritorial | 2006 |
| Commonside Management Company (Daresbury) Ltd | Administrative & support | 2014 |
| Communicam Limited | Health & social care | 2019 |
| Communications Agency Services Limited | Arts & recreation | 1995 |
| Communications Ombudsman Limited | Professional & scientific | 2022 |
| Community Care Matters Limited | Health & social care | 2007 |
| Community Care Solutions Limited | Health & social care | 2000 |
| Community Lettings Ltd | Real estate | 2018 |
| Community Objectives CIC | Arts & recreation | 2019 |
| Community Windpower Limited | Energy | 2002 |
| Companion Care North West Ltd | Health & social care | 2025 |
| Compass 13 Limited | Education | 2019 |
| Compass Catering Ltd | Hospitality | 2024 |
| Compass Evaluator Reports Limited | Professional & scientific | 2021 |
| Compass Point Productions Ltd | Information & communication | 2025 |
| Compassion in Action | Other services | 2009 |
| Compassionate Care Solutions NW Ltd | Health & social care | 2024 |
| Compec Electrical Installations Ltd | Manufacturing | 2018 |
| Complete Bar Solutions Ltd | Hospitality | 2026 |
| Complete Bathrooms NW Limited | Construction | 2023 |
| Complete Electrical Services Limited | Construction | 2007 |
| Complete Investments Group Ltd | Financial services | 2022 |
| Complete Management Limited | Professional & scientific | 2017 |
| Complete My Sale Ltd | Administrative & support | 2019 |
| Complete Offshore Limited | Professional & scientific | 2017 |
| Complete Psychology Limited | Professional & scientific | 2022 |
| Complete Recruit Consultants Ltd | Administrative & support | 2022 |
| Complete Roofing Systems Limited | Construction | 2010 |
| Completely Marketing Ltd | Professional & scientific | 2020 |
| Completely Strategy Limited | Administrative & support | 2021 |
| Completion Services Limited | Administrative & support | 2025 |
| Complex Core Services Ltd | Professional & scientific | 2022 |
| Complex Elec Ltd | Construction | 2024 |
| Complexar Limited | Professional & scientific | 2011 |
| Complexions Enterprise Ltd | Other services | 2010 |
| Compliance London Ltd | Professional & scientific | 2021 |
| Compliance Unlimited Ltd | Administrative & support | 2025 |
| Compliance-B Ltd | Professional & scientific | 2024 |
| Complisurv Ltd | Professional & scientific | 2024 |
| Compressor Parts Ltd | Wholesale & retail | 2025 |
| Compskill UK Ltd | Transport & logistics | 2018 |
| Computech Consultants Limited | Professional & scientific | 1990 |
| Compylex Ltd | Professional & scientific | 2020 |
| Comsap Ltd | Information & communication | 2019 |
| Comsilium Limited | Professional & scientific | 2024 |
| Comtec (Cheshire) Limited | Construction | 1995 |
| Comtech World Ltd | Wholesale & retail | 2018 |
| Comtract Services Ltd | Administrative & support | 2017 |
| Conal Walsh Project Management Limited | Professional & scientific | 2017 |
| Conan Investments Limited | Real estate | 2018 |
| Conarcap Partners Limited | Administrative & support | 2021 |
| Concava Ltd | Transport & logistics | 2020 |
| Concept Property Lets (UK) Limited | Real estate | 2018 |
| Concept Studios (MCR) Ltd | Arts & recreation | 2025 |
| CONCEPT101 Ltd | Administrative & support | 2023 |
| Concise Contract Services Limited | Professional & scientific | 2023 |
| Concision-Coding Limited | Information & communication | 2019 |
| Concorde Web Ltd | Information & communication | 2025 |
| Concordia Connections Ltd | Other services | 2024 |
| Concordia Electrical Services Ltd | Manufacturing | 2022 |
| Concussion Clinic Limited | Health & social care | 2015 |
| Condur Estates Limited | Real estate | 2023 |
| Coneng Limited | Administrative & support | 2023 |
| Conero Consulting Ltd | Information & communication | 2025 |
| Conet Warrington Ltd | Information & communication | 2021 |
| Confortare Limited | Information & communication | 2015 |
| Coniston Harrow Ltd | Professional & scientific | 2018 |
| Conker Payments and Utilities Ltd | Information & communication | 2024 |
| Conlon-Rail Limited | Construction | 2018 |
| Connatty Consulting Services Limited | Professional & scientific | 2018 |
| Connaught Training Services Limited | Extraterritorial | 2002 |
| Connect Asset Finance Ltd | Financial services | 2025 |
| Connect Commercial Services Limited | Administrative & support | 2024 |
| Connect Price Limited | Administrative & support | 2012 |
| Connect Services North West Limited | Administrative & support | 2016 |
| Connectivity Infrastructure Limited | Construction | 2023 |
| Connexus Education Ltd | Education | 2022 |
| Connexus Group Limited | Financial services | 2017 |
| Connexus Health Solutions Limited | Health & social care | 2008 |
| Connexus Insurance Solutions Limited | Financial services | 1998 |
| Connexus Medical Appointments Limited | Other services | 2011 |
| Connexus Vehicle Solutions Limited | Administrative & support | 2025 |
| Connor Christmas Consulting Limited | Professional & scientific | 2006 |
| Conntech Solutions Ltd | Administrative & support | 2013 |
| Conor Rogers Consulting Ltd | Professional & scientific | 2023 |
| Consecutive Operations Limited | Administrative & support | 2016 |
| Consilium Agon Ltd | Information & communication | 2026 |
| Consilium Business Consultants Ltd | Public administration | 2018 |
| Consilium Contracting Solutions Limited | Administrative & support | 2018 |
| Consit Limited | Information & communication | 2015 |
| Conspicuous Moth Ltd | Information & communication | 2014 |
| Constantin Bobleaga 0170 Limited | Administrative & support | 2016 |
| Constellation Engineering Limited | Administrative & support | 2014 |
| Construction Health and Safety Management Ltd | Administrative & support | 2024 |
| Construction Inspector Services Ltd | Construction | 2024 |
| Construction Materials Marketing Ltd | Construction | 2017 |
| Construction Project and Cost Management Limited | Professional & scientific | 2007 |
| Constructsys Limited | Information & communication | 2015 |
| Consultants 4 IT Ltd | Information & communication | 2007 |
| Consulting Cube Limited | Professional & scientific | 2013 |