| Combstock Installations Limited | Construction | 2017 |
| Come GET ME Taxis Ltd | Extraterritorial | 2022 |
| Come to Sardinia Limited | Administrative & support | 2004 |
| Comely Development Ltd | Construction | 2026 |
| Comicoffee UK Limited | Hospitality | 2021 |
| Commercial 2020 Ltd | Other services | 2018 |
| Commercial Contracting (IW) Ltd | Administrative & support | 2025 |
| Commercial House Abercarn Ltd | Education | 2020 |
| Commercial Installations and Solutions Limited | Manufacturing | 2014 |
| Commercial Kurd Barbers Ltd | Other services | 2025 |
| Commercial Motors Limited | Real estate | 1996 |
| Commercial Valeting Services (SW) Ltd | Other services | 2009 |
| Commissioning Systems Ltd | Information & communication | 2011 |
| Comms Creatives Ltd | Professional & scientific | 2014 |
| Community Action Isle of Wight | Administrative & support | 1997 |
| Community House, Eton Road | Health & social care | 2009 |
| Community IT Support CIC | Education | 2022 |
| Company Asset Finance Limited | Financial services | 2014 |
| Compass Business Broker Ltd | Administrative & support | 2020 |
| Compass Careers Limited | Administrative & support | 2013 |
| Compass Point (Swanage Grammar School) Management Company Limited | Households | 2021 |
| Compass Point (Swanage) Management Company Limited | Households | 2019 |
| Compcity Limited | Wholesale & retail | 2020 |
| Complete Clean Ltd | Administrative & support | 2021 |
| Complete Controls (Western) Limited | Professional & scientific | 2017 |
| Complete Servicing Solutions Ltd | Education | 2013 |
| Compo Tech Developments UK Ltd | Professional & scientific | 2024 |
| Compound Semiconductor Applications Catapult Limited | Professional & scientific | 2016 |
| Compressed Air Systems Limited | Energy | 2015 |
| Conbury Composites Limited | Manufacturing | 1969 |
| Concept Ductwork Manufacturing Limited | Manufacturing | 2020 |
| Concept Electrical Contractors (IW) Ltd | Construction | 2008 |
| Concept Logistics Ltd | Transport & logistics | 2022 |
| Concept Plumbing and Heating Limited | Construction | 2017 |
| Concept Staffing Limited | Administrative & support | 1988 |
| Concerts for Good Causes Ltd | Arts & recreation | 2024 |
| Concrete City Limited | Construction | 2021 |
| Conemasters Limited | Professional & scientific | 2002 |
| Coney Island Ice Cream CYF. | Hospitality | 2022 |
| Confide Care Ltd | Health & social care | 2025 |
| Confidenza Limited | Information & communication | 2022 |
| Configur Ltd | Information & communication | 2019 |
| Configuration Solutions Limited | Professional & scientific | 2017 |
| Conia Ltd | Wholesale & retail | 2025 |
| Coniston & Windermere (Isle of Wight) Management Company Limited | Households | 2001 |
| Connect 24/7 SSP Ltd | Information & communication | 2025 |
| Connect Consultants Employee Ownership Trustee Limited | Professional & scientific | 2024 |
| Connect Consultants Limited | Professional & scientific | 2006 |
| Connect S.W. Electrical Services Limited | Construction | 2007 |
| Connect to Successes Ltd | Health & social care | 2019 |
| Connected Counselling Limited | Health & social care | 2022 |
| Connecting Electrical Contractors Ltd | Construction | 2021 |
| Connexcel School Ltd | Real estate | 2017 |
| Connexus Limited | Administrative & support | 2023 |
| Consili Consulting Ltd | Information & communication | 2018 |
| Consortia Management Limited | Households | 2013 |
| Conspiracy (Cardiff) Trading Ltd | Hospitality | 2020 |
| Constant Property Solutions Limited | Real estate | 2025 |
| Constantine LVS Limited | Transport & logistics | 2020 |
| Construct IW Ltd | Construction | 2019 |
| Construction and Roofing Services Limited | Information & communication | 2024 |
| Construction Excellence in Wales Limited | Administrative & support | 2017 |
| Construction MP Ltd | Construction | 2024 |
| Consult-Air Ltd | Professional & scientific | 2023 |
| Consultants Secretarial Services Ltd | Administrative & support | 2023 |
| Contact Radio Communications Limited | Manufacturing | 1990 |
| Container Cuts Ltd | Other services | 2025 |
| Content for Socials Ltd | Information & communication | 2025 |
| Context Consultancy Ltd Limited | Administrative & support | 2017 |
| Conti Fish Bar(Uk) Ltd | Wholesale & retail | 2017 |
| Continental Wood Limited | Extraterritorial | 2024 |
| Continental Wood Products Limited | Extraterritorial | 2024 |
| Continuas Consultancy Ltd | Professional & scientific | 2012 |
| Continuous Pharmaceuticals Limited | Manufacturing | 2016 |
| Continuous Technologies Limited | Information & communication | 2026 |
| Contract Wise Holdings Limited | Financial services | 2025 |
| Contract Wise Limited | Professional & scientific | 2023 |
| Contract Wise Solutions Limited | Professional & scientific | 2025 |
| Contractors Quantity Surveying and Project Management Limited | Professional & scientific | 2018 |
| Convey Investments Limited | Real estate | 2021 |
| Convey Law Group Ltd | Professional & scientific | 2008 |
| Convey Law Ltd. | Professional & scientific | 2004 |
| CONVEY365 Ltd | Professional & scientific | 2009 |
| CONVEY365IT Limited | Information & communication | 2021 |
| Coobros Ltd | Real estate | 2019 |
| Cook and Baker IOW Limited | Hospitality | 2010 |
| Cook Avenue Maisonettes RTM Company Limited | Professional & scientific | 2006 |
| Cook Tyres Limited | Wholesale & retail | 2023 |
| Cookies Electrical Ltd | Construction | 2023 |
| Coombe Barn 2025 Ltd | Other services | 2008 |
| Coopers Amusements Limited | Arts & recreation | 2024 |
| Cooze Coms Limited | Information & communication | 2023 |
| Copa Chiropractic Limited | Health & social care | 2023 |
| Copilot Paraplanning Limited | Financial services | 2020 |
| Copmed Ltd | Health & social care | 2018 |
| Copper Logs Limited | Agriculture & fishing | 2020 |
| Coral Creative Ltd | Professional & scientific | 2026 |
| Cord Entertainment Ltd | Information & communication | 2021 |
| Core Groundworks & Utilities Ltd | Construction | 2018 |
| Core Value Properties Ltd | Real estate | 2021 |