| Connect (Shopfitting) Interiors Ltd. | Construction | 2010 |
| Connect Network Services Limited | Information & communication | 2004 |
| Connect Surveys Limited | Construction | 2023 |
| Connected Pathways Therapy Ltd | Health & social care | 2020 |
| Conservatory Florist Ltd | Wholesale & retail | 2013 |
| Conservatoryland Limited | Manufacturing | 1999 |
| Consolidated Coatings Ltd | Construction | 1992 |
| Constantin Trans Bucovina Ltd | Administrative & support | 2024 |
| Constantin's Services Limited | Information & communication | 2025 |
| Construction an Ltd | Construction | 2025 |
| Construction Personnel Specialists Ltd | Construction | 2019 |
| Consult SUE Carter Ltd | Professional & scientific | 2021 |
| Contract Review UK Limited | Professional & scientific | 2026 |
| Controller X Ltd | Wholesale & retail | 2024 |
| Copper Bay Creative Ltd | Information & communication | 2010 |
| Copt Hill Property Ltd | Real estate | 2023 |
| Corbett Property Investments Holdings Limited | Financial services | 2017 |
| Corbett Property Investments Limited | Real estate | 2017 |
| Core-Ect Diamond Drilling Limited | Construction | 2021 |
| Corestate Collective Ltd | Wholesale & retail | 2026 |
| Cornell & Carter Plastering & Drylining Ltd | Construction | 2006 |
| Cornerstone Wealth Planning Limited | Professional & scientific | 2015 |
| Cortez Limited | Households | 2017 |
| Cory Wallace Ltd | Wholesale & retail | 2025 |
| Cosmicsbox Ltd | Other services | 2018 |
| Cosmilar Services Ltd | Transport & logistics | 2020 |
| Cosmin Bespoke Ltd | Construction | 2020 |
| Costa Services Ltd | Transport & logistics | 2019 |
| Cosy Little Home Ltd | Manufacturing | 2018 |
| Cosy Nest Cleaning Ltd | Administrative & support | 2025 |
| Countryside Solution Services Ltd | Construction | 2025 |
| Coupling Protection Systems Limited | Professional & scientific | 2004 |
| Courio Limited | Information & communication | 2020 |
| Courson Medical Solutions Ltd | Health & social care | 2020 |
| Cowens Employee Benefits Limited | Financial services | 2013 |
| Cowens Mortgage Solutions Limited | Financial services | 2021 |
| CP Motors&More Ltd | Wholesale & retail | 2025 |
| CPM Surveys Limited | Construction | 2006 |
| CPS (Midlands) Ltd | Other services | 2008 |
| Cpsc Specialists Ltd | Construction | 2024 |
| CQ Medical Limited | Professional & scientific | 2013 |
| CQ Orthopaedics Ltd | Health & social care | 2019 |
| Craft Shapes Direct Limited | Arts & recreation | 2019 |
| Craig J Anderson Ltd | Manufacturing | 2019 |
| Craig Savage Music Limited | Information & communication | 2025 |
| Crates & Grapes Limited | Hospitality | 2026 |
| CRE Catering Ltd | Hospitality | 2026 |
| Creast Healthcare Ltd | Health & social care | 2021 |
| CREAT8 Limited | Professional & scientific | 2022 |
| Creative Asset Ltd | Information & communication | 2016 |
| Creative Cornwall Ltd | Professional & scientific | 2025 |
| Creative Enhancement Ltd | Health & social care | 2011 |
| Creative Luxury Living Limited | Real estate | 2026 |
| Creative Marketing Support Ltd | Professional & scientific | 2020 |
| Creative Projects (Mids) Ltd | Administrative & support | 2009 |
| Creative Soul Records Limited | Wholesale & retail | 2019 |
| Creative Steelwork Limited | Manufacturing | 2005 |
| Creativefive Holdings Limited | Real estate | 2022 |
| Creativefive Ltd | Information & communication | 2014 |
| Creed Medical Ltd | Other services | 2018 |
| Cricket World Media Limited | Information & communication | 2007 |
| Criminal Clothing Ltd. | Extraterritorial | 2001 |
| Crispr Diagnostics Ltd | Professional & scientific | 2020 |
| Crocodile Rock Daycare Limited | Other services | 2018 |
| Croflo Motors Limited | Wholesale & retail | 2014 |
| Croft M & E Services Ltd | Construction | 2022 |
| Croft Property Investments Ltd | Households | 2023 |
| Crofts Installations Limited | Extraterritorial | 2008 |
| Crombie&Co Ltd | Wholesale & retail | 2026 |
| Crook Business and Co Limited | Other services | 2025 |
| Cross Lane Equestrian Limited | Agriculture & fishing | 2003 |
| Crosscurrents Consulting Ltd | Professional & scientific | 2025 |
| Crown Green Development Limited | Households | 2018 |
| CRS FP Holdings Ltd | Financial services | 2025 |
| Crusty Crew Ltd | Hospitality | 2025 |
| CRX Safety Training & Consultancy Ltd | Professional & scientific | 2021 |
| Crynant Ltd | Manufacturing | 2015 |
| Cryscart Ltd | Information & communication | 2026 |
| Crystal Clear HR Solutions Limited | Professional & scientific | 2007 |
| Crystal Homes Limited | Real estate | 1996 |
| Crystal Knitwear Limited | Manufacturing | 2012 |
| Crystal Lace Company Limited(The) | Real estate | 1928 |
| CS and DS Properties Ltd | Real estate | 2012 |
| CS and MS Properties Ltd | Real estate | 2024 |
| CS Mansfield Ltd | Financial services | 2026 |
| CS Recruit Ltd | Administrative & support | 2021 |
| CS Sports and Activity Ltd | Arts & recreation | 2021 |
| CSB Homes Limited | Real estate | 2016 |
| CSE Building Services Ltd | Construction | 2017 |
| CSF Accountancy Limited | Professional & scientific | 2014 |
| CSL Plastering & Rendering Services Ltd | Construction | 2026 |
| CSS Commercial Limited | Real estate | 2010 |
| Cswh Limited | Information & communication | 2025 |
| CT Asset Management Ltd | Real estate | 2019 |
| CT Mansfield Limited | Hospitality | 2024 |
| CTK Holdings Ltd | Real estate | 2026 |
| CTS Scaffolding Ltd | Construction | 2011 |
| CU Technical Services Limited | Professional & scientific | 2002 |
| CUB Rocks Ltd | Wholesale & retail | 2021 |
| Cube FM Limited | Administrative & support | 2020 |