| Church Lane Project Limited | Construction | 2010 |
| Church Properties Ltd | Real estate | 2017 |
| Church View (Sandown) Management Company Limited | Real estate | 2003 |
| Cicor Newport Ltd | Manufacturing | 1967 |
| CIG Calon Cymru 2010 CYF | Manufacturing | 2010 |
| Ciha Ltd | Education | 2025 |
| CII (Newport) Ltd | Hospitality | 2023 |
| Cilfeithy Ganol Limited | Energy | 2014 |
| Cineluxe Ltd | Arts & recreation | 2020 |
| Cinnamon Court Management Company (IW) Limited | Households | 2007 |
| Cintec International Limited | Manufacturing | 1985 |
| CIO Recruitment Ltd | Administrative & support | 2022 |
| Ciran Grill Ltd | Hospitality | 2018 |
| Circle Flat(Management)Co.Limited(The) | Households | 1971 |
| Circle Square 24 Ltd | Other services | 2020 |
| Circuitz Ltd | Manufacturing | 2024 |
| Circus of Positivity CIC | Arts & recreation | 2023 |
| Citi Financials Ltd | Information & communication | 2010 |
| Citizens Advice Isle of Wight Community Interest Company | Hospitality | 2024 |
| City Bites Ltd | Hospitality | 2021 |
| City Energies UK Ltd | Manufacturing | 2000 |
| City Export Packers Limited | Manufacturing | 2004 |
| City Fit Ltd | Arts & recreation | 2017 |
| City Locksmiths Gwent Limited | Manufacturing | 2012 |
| City of Newport Gymnastics Academy | Arts & recreation | 2013 |
| City Pest Control and Hygiene Ltd | Administrative & support | 2026 |
| City Speedway Ltd | Arts & recreation | 2008 |
| City Stone Masonry Ltd | Construction | 2025 |
| City Talent Investments (U K) Limited | Real estate | 2014 |
| City Testing Centre Limited | Wholesale & retail | 2004 |
| City Trade Ltd | Professional & scientific | 2004 |
| City Windows Newport Limited | Construction | 2011 |
| Cityresin Ltd | Construction | 2025 |
| CJD Auto Repairs Ltd | Wholesale & retail | 2026 |
| CJM Plumbing Services Limited | Construction | 2004 |
| Cjsed Limited | Professional & scientific | 2015 |
| CJT Home Improvements Limited | Construction | 2023 |
| Clara Partners Limited | Financial services | 2020 |
| Clare Griffin Optometrists Ltd | Wholesale & retail | 2020 |
| Claremont Building Solutions Ltd | Construction | 2016 |
| Clarence Court (Chepstow Road) Management Association Limited | Households | 1992 |
| Clarence Homes (Newport) Ltd | Water & waste | 2022 |
| Clarence House (Isle of Wight) Management Company Limited(The) | Households | 1978 |
| Clarence Removals Limited | Water & waste | 2026 |
| Clarendon Apartments Management Company Limited | Households | 2005 |
| Clarendon Court (Ventnor) Limited | Households | 2006 |
| Clarendon Press Management Limited | Households | 2004 |
| Clare’S Home Bakes Ltd | Manufacturing | 2019 |
| Clarissekumwena Healthcare Limited | Health & social care | 2023 |
| Clarity Coaching and Consulting Ltd | Real estate | 2021 |
| Clarity Compliance Solutions Limited | Professional & scientific | 2010 |
| Clarity Practice Organisation Limited | Information & communication | 2022 |
| Clark Contractors (Fire Protection Division) Ltd | Construction | 2022 |
| Clark Contractors Limited | Construction | 2006 |
| Clarus Sports Management Ltd | Arts & recreation | 2025 |
| Class Topper UK Ltd | Education | 2023 |
| Classic Car Vault Limited | Wholesale & retail | 2025 |
| Classic Fires & Bathrooms Limited | Construction | 2002 |
| Classic Stoves Limited | Professional & scientific | 2011 |
| Classic Yacht Events Ltd | Manufacturing | 2004 |
| Clat Agri Ltd | Agriculture & fishing | 2019 |
| Claybrook Management Service Limited | Real estate | 2010 |
| Clayton Court (Freshwater) Management Company Limited | Households | 1982 |
| Clean Cleaner Clean Limited | Administrative & support | 2022 |
| Clean Lines Decorators Ltd | Construction | 2022 |
| Cleanerbility Ltd | Information & communication | 2022 |
| Cleaning ANGEL25 Ltd | Administrative & support | 2026 |
| Cleaningall Limited | Administrative & support | 2020 |
| Cleanwise Commercial Services UK Limited | Administrative & support | 2012 |
| Clear Advice Mortgage Services Limited | Financial services | 2021 |
| Clear Choice Recruitment Ltd | Administrative & support | 2023 |
| Clear for MEN Ltd. | Wholesale & retail | 2021 |
| Clear OUT (UK) Limited | Water & waste | 2014 |
| Clear Space Consulting Ltd | Professional & scientific | 2024 |
| Clearpath Services Limited | Professional & scientific | 2019 |
| Clearstream Networks Ltd | Wholesale & retail | 2000 |
| Clearwater Care (Leadon Court) Limited | Health & social care | 2004 |
| Clearwater Electrical (Wales) Ltd | Construction | 2025 |
| Clever Business Centre Limited | Real estate | 2017 |
| Clewer Court Residents Limited | Hospitality | 1980 |
| CLG Scaffolding Ltd | Construction | 2026 |
| Clibborn Air Conditioning Ltd | Construction | 2023 |
| Click Commerce Ltd | Wholesale & retail | 2024 |
| Click-Mart Limited | Wholesale & retail | 2022 |
| Clicknest ADS Limited | Professional & scientific | 2026 |
| Clickvex Ltd | Wholesale & retail | 2026 |
| Clifton Finishers Ltd | Construction | 2019 |
| Clifton Quantity Surveying Ltd | Professional & scientific | 2025 |
| Clifton Subsea Services Limited | Administrative & support | 2017 |
| Climar Industries Limited | Construction | 2002 |
| Climax Promotions & Events Ltd | Administrative & support | 2020 |
| Clinical Innovations Europe Limited | Health & social care | 2014 |
| Clinicmind Ltd | Information & communication | 2023 |
| Clive Mathias Limited | Professional & scientific | 2000 |
| Cloud 9 Fashion Limited | Wholesale & retail | 2016 |
| Cloud UK Networks Ltd | Information & communication | 2026 |
| Cloudseller UK Ltd | Wholesale & retail | 2019 |
| CLP (Bristol) Limited | Construction | 2019 |
| CLR Property Ltd | Real estate | 2015 |
| Clrk Design Limited | Professional & scientific | 2025 |