| CJN Plant and Driver Hire Ltd | Construction | 2020 |
| CJT Timber Sourcing Ltd | Manufacturing | 2023 |
| CJW Fabrications Limited | Manufacturing | 2023 |
| Ckdt Holding Ltd | Professional & scientific | 2023 |
| CKM Fitness Ltd | Arts & recreation | 2010 |
| CL Equestrian Centre Ltd | Agriculture & fishing | 2025 |
| CL Mobile Welding & SON Ltd | Construction | 2004 |
| CL Textiles Ltd | Wholesale & retail | 2025 |
| Clad/Steel Limited | Construction | 2016 |
| Cladtech Ltd | Construction | 2026 |
| Claims Solution UK Limited | Administrative & support | 2007 |
| Claire Davies Interiors Limited | Other services | 2017 |
| Claire Dowd Events Limited | Administrative & support | 2016 |
| Claire Houston Therapy Ltd | Professional & scientific | 2021 |
| Claire Quick Studio Limited | Administrative & support | 2024 |
| Claj Properties Limited | Extraterritorial | 2016 |
| Clam-Co (Management) Ltd | Real estate | 2011 |
| Clanbrassil Consulting Ltd | Professional & scientific | 2025 |
| Clancy Group (NW) Limited | Wholesale & retail | 2024 |
| Claraalexanderuk Ltd | Manufacturing | 2018 |
| Clareo Health Limited | Information & communication | 2025 |
| Clariana Ltd | Information & communication | 2025 |
| Claritax Books Limited | Information & communication | 2011 |
| Clark Developments Limited | Construction | 2023 |
| Clark Mortgages Ltd | Financial services | 2022 |
| Clarkson's Maritime Services Ltd | Transport & logistics | 2023 |
| Clarren Construction Limited | Construction | 2017 |
| Classe Properties Ltd | Real estate | 2026 |
| Classic Treats Limited | Wholesale & retail | 2022 |
| Classie Dog Products Ltd | Other services | 2024 |
| Classix Solutions Limited | Professional & scientific | 2019 |
| Clause Limited | Professional & scientific | 2018 |
| Claverton Chester LLP | | 2013 |
| Clavis Limited | Construction | 2022 |
| Clayfield Yilmaz Limited | Wholesale & retail | 2021 |
| Claymore Business Machines Limited | Administrative & support | 1990 |
| Clayton House Management Company Limited | Real estate | 1987 |
| Clayton Recruitment Limited | Administrative & support | 2001 |
| Clean 365 Limited | Water & waste | 2009 |
| Clean Air Services Ltd | Manufacturing | 2018 |
| Clean Commercial Limited | Administrative & support | 2011 |
| Clean Slate Chester Ltd | Administrative & support | 2018 |
| Cleaning With Passion Limited | Administrative & support | 2025 |
| Cleantech Civils Ltd. | Construction | 2011 |
| Clear Beauty Limited | Other services | 2025 |
| Clear Cloud Computing Services Limited | Information & communication | 2011 |
| Clear Consulting Group Ltd. | Professional & scientific | 2013 |
| Clear Mediation Ltd | Professional & scientific | 2013 |
| Clearbox Consulting Limited | Professional & scientific | 2006 |
| Clearbuild Limited | Real estate | 2001 |
| Cleaver Developments Limited | Real estate | 2013 |
| Clelida Ltd | Health & social care | 2022 |
| Clemency & Grit Ltd | Construction | 2016 |
| Clement Management Ltd | Households | 2015 |
| Clever Adviser Technology Limited | Information & communication | 1994 |
| Clever Brick Finance Limited | Financial services | 2019 |
| Clever Investment Management Ltd | Financial services | 2022 |
| Click Aviation Network Ltd | Extraterritorial | 2014 |
| Clickacall Limited | Information & communication | 2019 |
| Clickbooking.Online Ltd | Hospitality | 2023 |
| Cliffdales Bespoke Design Limited | Manufacturing | 2021 |
| Clifford Jones Holdings Ltd | Financial services | 2023 |
| Climatised Coatings (U.K.) Limited | Construction | 1994 |
| Climb and Balance Ltd | Other services | 2022 |
| Climbhq Ltd | Professional & scientific | 2025 |
| Climbing Stars Ltd | Professional & scientific | 2025 |
| Clinic Motion Media Limited | Professional & scientific | 2014 |
| Clive Terry Heating Services Ltd | Construction | 2006 |
| Clock Records Limited | Information & communication | 2010 |
| Cloganic Ltd | Professional & scientific | 2025 |
| Cloka Enterprises Ltd | Wholesale & retail | 2020 |
| Clos TY Mawr Management Limited | Households | 2025 |
| Cloud and Telecom Services Limited | Information & communication | 2021 |
| Cloud Mandarin Ltd | Information & communication | 2023 |
| Cloud Vending Limited | Wholesale & retail | 2022 |
| Cloudchain Ltd | Information & communication | 2018 |
| Cloudis Limited | Information & communication | 1994 |
| Clover Care Group Limited | Public administration | 2024 |
| Clover Talent Limited | Administrative & support | 2024 |
| CLR Holdings Limited | Wholesale & retail | 2021 |
| Clsg Limited | Professional & scientific | 2019 |
| Cltd Electrical Ltd | Construction | 2026 |
| Club Control Limited | Information & communication | 2014 |
| Club Survivor Ltd | Information & communication | 2026 |
| Clumsy Monkey Ltd | Hospitality | 2021 |
| Clwyd Auto Electrical Ltd | Wholesale & retail | 2016 |
| Clwyd Services Limited | Administrative & support | 2002 |
| CMB Inns Limited | Hospitality | 2021 |
| CMC Business Psychology Ltd | Professional & scientific | 2017 |
| CMC Distributors Ltd | Wholesale & retail | 2022 |
| CME in the Community CIC | Health & social care | 2011 |
| CMK Capital Finance Group Limited | Professional & scientific | 2025 |
| Cmt-Tech Limited | Information & communication | 2010 |
| CNR UK (NCR UK) Ltd | Wholesale & retail | 2022 |
| CNS IT Limited | Information & communication | 2006 |
| CNS Technology Ltd | Wholesale & retail | 2025 |
| CNW Fire Solutions Ltd | Public administration | 2023 |
| CNW Renewables Ltd | Construction | 2025 |
| Cnwfood&Drinkfestival Ltd | Administrative & support | 2025 |
| Co Hoole Limited | Administrative & support | 2025 |