| Coffee Friends Ltd | Hospitality | 2025 |
| Coffeedaze Ltd | Professional & scientific | 2022 |
| Cogitamus Limited | Professional & scientific | 2007 |
| Cognitionsys Limited | Information & communication | 2013 |
| Cognizia Ltd | Information & communication | 2015 |
| Cola Leisure CIC | Arts & recreation | 2024 |
| Cola Ship Limited | Arts & recreation | 2024 |
| Colbert Plumbing and Heating Limited | Construction | 2020 |
| Cold Hire Services Limited | Administrative & support | 2022 |
| Coldtap Limited | Information & communication | 2008 |
| Coleman Investment Group Ltd | Professional & scientific | 2022 |
| Coleman Investment Properties Ltd | Real estate | 2024 |
| Coleridge Heath Ltd | Wholesale & retail | 2024 |
| Coles Pension Services Limited | Professional & scientific | 2009 |
| Colin & ANN Harris Limited | Wholesale & retail | 2004 |
| Collabcfo Ltd | Professional & scientific | 2025 |
| Collaborative Property Development Ltd | Real estate | 2016 |
| Collabrum Private Limited | Wholesale & retail | 2022 |
| Collected Digital Limited | Information & communication | 2020 |
| Collectors Corner Ltd | Wholesale & retail | 2024 |
| College Street Properties Limited | Real estate | 2005 |
| Colliers Rest Management Company Limited | Households | 2026 |
| Collins Investments Group Limited | Financial services | 2026 |
| Collins Servs & Co Limited | Information & communication | 2026 |
| Collins-Few Developments Limited | Construction | 2026 |
| Collinson Rail Management Solutions Ltd | Professional & scientific | 2022 |
| COLLINSRIC911 Ltd | Professional & scientific | 2025 |
| Colltech Ltd | Professional & scientific | 2025 |
| Collyer Capital Ltd | Real estate | 2023 |
| Collyweston Roofing Ltd | Construction | 2010 |
| Colmworth Business Park Management Company Limited | Households | 2002 |
| Coloplast Limited | Wholesale & retail | 1973 |
| Coloplast Medical Limited | Extraterritorial | 2001 |
| Colossal Squid Ltd | Arts & recreation | 2016 |
| Colsterworth Holdings (2018) Limited | Financial services | 2018 |
| Columbus Computer Services Limited | | 1986 |
| Colyer Consulting Ltd | Information & communication | 2012 |
| Colyer Housing Ltd | Real estate | 2022 |
| Combat Gear Ltd | Wholesale & retail | 2026 |
| Combi Services Ltd | Construction | 2021 |
| Combi-Tech Engineering Services Ltd | Professional & scientific | 2024 |
| Combilift Ltd | Extraterritorial | 2015 |
| Comequip Ltd | Wholesale & retail | 2015 |
| Cometstream Limited | Information & communication | 1993 |
| Comfort Heating and Plumbing Ltd | Construction | 2026 |
| Comfort Property Management (CPM) Ltd. | Real estate | 2019 |
| Commerce Road Ltd | Manufacturing | 2022 |
| Commercial Construction Solutions Ltd | Professional & scientific | 2026 |
| Commercial Signs Limited | Manufacturing | 2013 |
| Commercial Spares and Breakers Ltd | Wholesale & retail | 2025 |
| Commercial Surveyor Ltd | Professional & scientific | 2012 |
| Commercial Training Services (UK) Ltd | Education | 2011 |
| Commission Air Limited | Professional & scientific | 2012 |
| Commission Grove Ltd | Manufacturing | 2021 |
| Commitment to Care Ltd | Health & social care | 2011 |
| Common Pursuit Limited | Wholesale & retail | 2024 |
| Communications Trade Supplies Manufacturing Limited | Manufacturing | 1993 |
| Communitea Gaming Limited | Wholesale & retail | 2024 |
| Community at Heart CIC | Education | 2026 |
| Community Bilingual Services Ltd | Other services | 2013 |
| Community Links Media Limited | Professional & scientific | 2025 |
| Community Mosaic CIC | Real estate | 2018 |
| Companion Care Plus Ltd | Health & social care | 2024 |
| Company Forward Limited | Administrative & support | 2012 |
| Compare More Limited | Professional & scientific | 2018 |
| Compare the Market Limited | Administrative & support | 2017 |
| Comparison UK Limited | Financial services | 2018 |
| Compass Key for Engineering & Contracting Ltd | Wholesale & retail | 2022 |
| Compassionate Care GM Ltd | Health & social care | 2021 |
| Competitive Cleaning Services Limited | Administrative & support | 2017 |
| Compleat Care (UK) Limited | Health & social care | 1993 |
| Complete Care Matters Ltd | Health & social care | 2022 |
| Complete Farming & Contracting Co Ltd | Agriculture & fishing | 2019 |
| Complete Fibre Networks Limited | Information & communication | 2022 |
| Complete Fibre Solutions Ltd | Construction | 2023 |
| Complete Fleet Automotive Ltd | Wholesale & retail | 2024 |
| Complete Framing Limited | Manufacturing | 2009 |
| Complete Plumbing & Heating Services Ltd | Construction | 2022 |
| Compliance Medical Services Ltd | Health & social care | 2021 |
| Compote Consulting Limited | Professional & scientific | 2019 |
| Compton Bassett (NO 2) Residents Company Limited | Households | 2002 |
| Compton House Developments Limited | Real estate | 2015 |
| Computer MAN IT Services Ltd | Other services | 2021 |
| Computers Etsetra Limited | Wholesale & retail | 2021 |
| Computrix Ltd | Wholesale & retail | 2013 |
| Comuni-Co Language Coaching & Services Ltd | Education | 2018 |
| Conaco Construction Services Limited | Construction | 2010 |
| Conah Consulting Limited | Professional & scientific | 2022 |
| Conah Properties Limited | Real estate | 2020 |
| Concept Aluminium Ltd | Manufacturing | 2021 |
| Concept City Limited | Financial services | 2023 |
| Concept Properties Holdings Ltd | Construction | 2024 |
| Concierge DU Parfum Limited | Wholesale & retail | 2025 |
| Concrete Renovations Limited | Construction | 2009 |
| Confidence Connoisseur Ltd | Professional & scientific | 2018 |
| Confident Learners Ltd | Education | 2022 |
| Confluence Social Work Solutions Ltd | Health & social care | 2024 |
| Coningsby (West Drive) Residents Company Limited | Households | 2004 |
| Conington Flying Club Ltd | Hospitality | 2026 |
| Conington Hangar Company Ltd | Transport & logistics | 2026 |