| Clean Team (EA) Limited | Administrative & support | 2006 |
| Clear Vision Healthcare Limited | Health & social care | 2008 |
| Clear Vision Opticians Limited | Health & social care | 2024 |
| Clearbland Solutions Ltd | Administrative & support | 2025 |
| Clenergy Limited | Professional & scientific | 2023 |
| Clenergy Property Limited | Real estate | 2025 |
| Cleveland Joinery (East Anglia) Limited | Manufacturing | 2002 |
| Clover Competitions Limited | Wholesale & retail | 2020 |
| Clover Energies Ltd | Professional & scientific | 2024 |
| Clutten Consultancy Services Limited | Professional & scientific | 2005 |
| Clyffe Hotel Management Company Ltd | Hospitality | 2022 |
| Cmats (Eastern) Limited | Professional & scientific | 1999 |
| CMC Pubs Limited | Hospitality | 2025 |
| CMC07 Ltd | Hospitality | 2026 |
| CMD Consultancy Ltd | Professional & scientific | 2020 |
| CMV Automotive Limited | Wholesale & retail | 2016 |
| CNR Barbers Limited | Other services | 2023 |
| Coachingbycj Ltd | Other services | 2022 |
| Coast to Coast Lettings Ltd | Real estate | 2024 |
| Coast to Coast Limited | Wholesale & retail | 2003 |
| Coastal Cuisine Ltd | Manufacturing | 2021 |
| Coastal Keys Ltd | Real estate | 2025 |
| Coastal Marine Support Limited | Construction | 2020 |
| Coastal Real Estate Limited | Real estate | 2021 |
| Coastline Carpets Limited | Wholesale & retail | 2012 |
| Coastline Electrical (Waveney) Limited | Construction | 2013 |
| Coastline Training Solutions Limited | Education | 2019 |
| Coco Cares London Ltd | Other services | 2022 |
| Code Hair Consultants Limited | Other services | 2009 |
| Codenest Solution Ltd | Transport & logistics | 2025 |
| Codling Building and Landscaping Ltd | Construction | 2020 |
| Coenraad Ltd | Information & communication | 2023 |
| Cofetaria Gabriela's Cakes Lowestoft Ltd | Manufacturing | 2023 |
| Cohart Limited | Real estate | 2025 |
| Cohen Marine Enterprises Limited | Administrative & support | 2005 |
| Cole Property Services Limited | Real estate | 2020 |
| Coleman Medical Services Limited | Health & social care | 2014 |
| Coles Steel Fabricators Limited | Manufacturing | 2016 |
| Colin Brown Property Services Limited | Real estate | 2003 |
| Collaborations Case Management Limited | Health & social care | 2025 |
| Colnick Limited | Administrative & support | 2023 |
| Colonial Court Leiston Limited | Real estate | 2023 |
| Colourful Grey Limited | Professional & scientific | 2009 |
| Colville Road M.O.T. Centre Ltd | Wholesale & retail | 2006 |
| Colwells Driving Tuition Limited | Education | 2009 |
| Comac Consultants Limited | Professional & scientific | 2010 |
| Combat Offshore Solutions Limited | Mining & quarrying | 2014 |
| Combat Property Solutions Limited | Real estate | 2016 |
| Combo Asia Food Ltd | Hospitality | 2022 |
| Commercial Property & Rent Ltd | Administrative & support | 2024 |
| Commercial Support Services Limited | Wholesale & retail | 2004 |
| Communication Consultants (UK) Limited | Professional & scientific | 1995 |
| Communications Design and Technology Limited | Information & communication | 2002 |
| Community Rail Norfolk | Information & communication | 2011 |
| Compass Agencies Ltd | Financial services | 2014 |
| Compassionate Cremations Limited | Extraterritorial | 2024 |
| Complete Well Services Limited | Mining & quarrying | 1996 |
| Computer Forensics Online Limited | Information & communication | 2008 |
| Comta Limited | Professional & scientific | 2015 |
| Concrete Cyning Ltd | Construction | 2025 |
| Conolly Tech Services Ltd | Professional & scientific | 2024 |
| Conscious by Nature Limited | Wholesale & retail | 2020 |
| Conscious Kids Ltd | Professional & scientific | 2021 |
| Conservatory Bases Direct Limited | Construction | 2001 |
| Constructivate Ltd | Construction | 2024 |
| Contact Accountants Ltd | Professional & scientific | 2025 |
| COO Farm Ltd | Health & social care | 2025 |
| Coogan Holdings Limited | Real estate | 2017 |
| Cool Cats Air Conditioning Services Limited | Energy | 2022 |
| Coombes Contracting Ltd | Professional & scientific | 2017 |
| Cooper and Sons Heating and Renewable Energy Specialist Ltd | Construction | 2021 |
| Cooper and Sons Plumbing and Heating Ltd | Construction | 2010 |
| Cooper Law Limited | Other services | 2013 |
| Cooper Legal Limited | Other services | 2016 |
| Coote Finance Limited | Financial services | 2021 |
| Copperfields Blundeston Limited | Wholesale & retail | 2023 |
| Coppice Consult Limited | Professional & scientific | 2024 |
| Core-Legacy Limited | Professional & scientific | 2022 |
| Cork Electrical Limited | Manufacturing | 2017 |
| Corrconsult Ltd | Professional & scientific | 2019 |
| Corton Road Limited | Other services | 1998 |
| Costeng Limited | Professional & scientific | 2015 |
| Cotmer Properties Ltd | Real estate | 2016 |
| Country Chiropractic Limited | Extraterritorial | 2017 |
| Country Retirement & Nursing Homes (Holdings) Limited | Health & social care | 2008 |
| Country Retirement & Nursing Homes (Investments) Limited | Health & social care | 2008 |
| Country Retirement & Nursing Homes Ltd | Health & social care | 1999 |
| Courtney Cleans Ltd | Administrative & support | 2026 |
| Covill Interiors Ltd | Construction | 2012 |
| Cowley Fletcher Developments Limited | Construction | 2006 |
| CPL Plymouth Ltd | Real estate | 2021 |
| Craftwork Conservatories and Windows Limited | Construction | 2004 |
| Craig Thompson Oulton Broad Limited | Wholesale & retail | 2012 |
| Creative Construction EA Limited | Construction | 2023 |
| Creative Hairdressing Limited | Other services | 2002 |
| Creative Resins and Renovations Ltd | Construction | 2019 |
| Cremtech Ltd | Manufacturing | 2019 |
| Crimson Gold Limited | Other services | 1997 |
| Cringecare Studio Ltd | Wholesale & retail | 2023 |
| Crisp Barbers Shop Limited | Other services | 2003 |