| Conestoga Partners Limited | Professional & scientific | 2014 |
| Conexus Solutions Limited | Administrative & support | 2012 |
| Connected Collective Holdings Limited | Extraterritorial | 2009 |
| Connected IOT Limited | Wholesale & retail | 2025 |
| Connected PR Limited | Professional & scientific | 2006 |
| Connections Properties Limited | Construction | 2001 |
| Connell Guides Publishing Limited | Information & communication | 2011 |
| Connell Publishing Limited | Information & communication | 2017 |
| Connerty Group Ltd | Financial services | 2025 |
| Conservatory Buildings Limited | Construction | 2014 |
| Constellation Software UK Holdco Ltd | Information & communication | 2014 |
| Constrat Limited | Administrative & support | 2011 |
| Consultio Slash Consultius Ltd | Financial services | 2024 |
| Contemporary Counters Limited | Administrative & support | 2007 |
| Content Builder Limited | Information & communication | 2009 |
| CONTENT27 Limited | Education | 2020 |
| Continuous Improvement Training and Research Associates Limited | Education | 2015 |
| Continuum Connected Consulting Limited | Professional & scientific | 2015 |
| Control Tower Productions Ltd | Information & communication | 2020 |
| Convergence S.P.A.C.E Ltd | Information & communication | 2026 |
| Conygre Farm Ltd | Agriculture & fishing | 2011 |
| Cooke Corporate Holdings Limited | Financial services | 2023 |
| Cooke Corporations Limited | Professional & scientific | 2020 |
| Cooke Property Ltd | Professional & scientific | 2023 |
| Coombe Castle International Limited | Wholesale & retail | 1980 |
| Coponis Limited | Real estate | 2013 |
| Copper FOX Accountants Limited | Professional & scientific | 2020 |
| Coppice Close (Brooklands) Management Company Limited | Households | 2009 |
| Core Holdings (South West) Limited | Other services | 2015 |
| Corethree Ltd | Information & communication | 2009 |
| Corinium Precision Engineering Limited | Agriculture & fishing | 2003 |
| Cornflake Cottage Ltd | Hospitality | 2022 |
| Corporate IT Systems Limited | Information & communication | 2005 |
| Corsham Auto Repairs Ltd | Wholesale & retail | 2014 |
| Corsham Consulting Limited | Professional & scientific | 2016 |
| Corsham Estate Limited | Hospitality | 2014 |
| Corsham Print Ltd | Manufacturing | 2001 |
| Corsham Sponsors Refugees | Professional & scientific | 2018 |
| Corsham Tyre Service Limited | Wholesale & retail | 2006 |
| Corsham Waste Collections Limited | Water & waste | 2022 |
| Corvia Connect Limited | Information & communication | 2025 |
| Corvita Limited | Information & communication | 2014 |
| Cosi Carpets Wiltshire Ltd | Construction | 2023 |
| Cotswold & Counties Limited | Construction | 2006 |
| Cotswold Coffee Roasters Ltd | Wholesale & retail | 2016 |
| Cotswold Edge Consulting Ltd | Professional & scientific | 2019 |
| Cotswold Energy Group Ltd | Construction | 2018 |
| Cotswold Networking Ltd | Administrative & support | 2025 |
| Cottrell Building Services Ltd | Construction | 2015 |
| Counting Beans Accounting Limited | Professional & scientific | 2011 |
| Country Classics (Classic Cars) Limited | Wholesale & retail | 1995 |
| Country Green Limited | Real estate | 2016 |
| Countrymoos Ltd | Extraterritorial | 2026 |
| County Property Consultants Limited | Professional & scientific | 2001 |
| Courier Staffing Ltd | Transport & logistics | 2026 |
| Court Farm (Great ELM) CR Limited | Construction | 2022 |
| Cousin Norman's Ltd | Wholesale & retail | 2023 |
| Covered Occasions Limited | Administrative & support | 2005 |
| Coverleaf Limited | Agriculture & fishing | 1997 |
| Cowley Electrical Contractors Limited | Professional & scientific | 2007 |
| CPC Fencing Products Limited | Manufacturing | 2020 |
| CPM Sounds CIC | Information & communication | 2014 |
| CR Care and Support Ltd | Health & social care | 2020 |
| CR Engineering Ltd | Professional & scientific | 2026 |
| CR Houses Ltd | Real estate | 2017 |
| Craftscape Ltd | Construction | 2022 |
| Crafty POP Limited | Hospitality | 2019 |
| Craig John Holdings Limited | Information & communication | 2025 |
| Craig Mackrell Carpentry Ltd | Construction | 2023 |
| Crampton & Co (1896) Ltd | Wholesale & retail | 2016 |
| Crane Merchandising Systems Limited | Manufacturing | 1989 |
| Crash Car Body Repairs Limited | Wholesale & retail | 2003 |
| CRE8 Building Services Limited | Construction | 2017 |
| CRE8 Fire Protection Limited | Construction | 2024 |
| Creative Consultancy Group Limited | Professional & scientific | 2016 |
| Creative Floristry Limited | Other services | 2000 |
| Credit Efficiency Solutions Ltd | Professional & scientific | 2025 |
| Crescent Property Investments Limited | Real estate | 2022 |
| Crescent Renovations Limited | Construction | 2026 |
| Crispin Estates Limited | Real estate | 2008 |
| Crlrplg Limited | Administrative & support | 2018 |
| Crocus Farming Limited | Agriculture & fishing | 2019 |
| Crookall Advisory Limited | Professional & scientific | 2025 |
| Cross Border Financial Planning Limited | Financial services | 2016 |
| Crown Mews Trowbridge Limited | Households | 2022 |
| CRS Investment Holdings Ltd | Real estate | 2019 |
| Crypsis IT Services Ltd | Information & communication | 2015 |
| Crystal Clear Business Consulting Ltd | Professional & scientific | 2010 |
| Crystal JAY Consulting Limited | Information & communication | 2014 |
| CSA International Limited | Manufacturing | 1993 |
| Ctap Ltd | Information & communication | 2024 |
| CTC Arable Limited | Agriculture & fishing | 2010 |
| Cudon Limited | Hospitality | 2001 |
| Cultivated Learning Ltd | Education | 2015 |
| Cunliffe Consultants Limited | Information & communication | 2015 |
| CUP Half Full Co Ltd | Other services | 2026 |
| Cura Homecare (Chippenham) Ltd | Health & social care | 2012 |
| Curate Design Ltd | Wholesale & retail | 2021 |
| Curriculum Stories Limited | Education | 2026 |
| Curry Mirchi Limited | Hospitality | 2020 |