| Configuration Management Solutions Limited | Other services | 2026 |
| Conibear Contracting Ltd | Agriculture & fishing | 2015 |
| Conibear Holdings Limited | Financial services | 2024 |
| Conington Environmental Ltd | Professional & scientific | 2022 |
| Constant Growth Ltd | Information & communication | 2018 |
| Construct Lifts Limited | Construction | 2022 |
| Constructia Arch Ltd | Professional & scientific | 2025 |
| Construction Access Solutions Ltd | Construction | 2024 |
| Consultancy Growth Agency Ltd | Professional & scientific | 2022 |
| Consumer Champion Group Limited | Professional & scientific | 2009 |
| Consummate Care Limited | Health & social care | 2003 |
| Consummate Properties Ltd | Real estate | 2020 |
| Contact Centre Solutions Ltd | Professional & scientific | 2000 |
| Continuous Consultancy Limited | Professional & scientific | 2019 |
| Contract Printing Services Limited | Other services | 2003 |
| Convenient Stop Ltd | Wholesale & retail | 2024 |
| Conveyor Design Solutions Limited | Professional & scientific | 2023 |
| Convoy Logistics Ltd | Administrative & support | 2017 |
| Conway Logistic Solutions Limited | Transport & logistics | 2010 |
| Cook on Call Ltd | Hospitality | 2020 |
| Cooke's Books Limited | Professional & scientific | 2012 |
| Cooltouch Heaters Limited | Other services | 2013 |
| Cooney South Limited | Manufacturing | 2017 |
| Cooper and Harriet Properties Ltd | Real estate | 2022 |
| Cooper Armstrong Limited | Professional & scientific | 1983 |
| Cooper Footwear Limited | Manufacturing | 1990 |
| Cooper FOX Limited | Hospitality | 2025 |
| Cooper Road Ltd | Real estate | 2024 |
| Cooper Smith Properties Ltd | Real estate | 2022 |
| Coopers Garage Services Ltd | Wholesale & retail | 2024 |
| Copal Casting Limited | Extraterritorial | 2005 |
| Corby Kilns Limited | Manufacturing | 1996 |
| Core Care Provider Services Limited | Health & social care | 2020 |
| Core Carpentry Contractors Limited | Construction | 2023 |
| Core Comply UK Ltd | Construction | 2025 |
| Core Publications Limited | Manufacturing | 2008 |
| Corenso Group Holdings Limited | Financial services | 2014 |
| Corex (Wigan) Limited | Manufacturing | 1986 |
| Cornerstone Cards Ltd | Wholesale & retail | 2025 |
| Cornerstone Landscape Services Ltd | Administrative & support | 2020 |
| Cornwall Care Solution Limited | Health & social care | 2026 |
| Cortexa Limited | Information & communication | 2001 |
| Cortom Ltd | Construction | 2024 |
| Corvee Property Services Limited | Construction | 1997 |
| Cosy Accommodation Ltd | Real estate | 2017 |
| Cosy Stoves Installations Limited | Construction | 2025 |
| Cotchford Farm Limited | Agriculture & fishing | 2025 |
| Cotswold Glazing Craft Ltd | Construction | 2025 |
| Cottenham Developments Limited | Construction | 2016 |
| Cotterstock Education Ltd | Education | 2020 |
| Cottingham Engineering Limited | Other services | 2002 |
| Cottingham Groundworks and Landscaping Ltd | Manufacturing | 2019 |
| Cottingham Solutions Limited | Real estate | 2025 |
| Cougar Red Limited | Manufacturing | 2005 |
| Couloir Group Ltd | Financial services | 2024 |
| Couloir Property Consultants Ltd | Real estate | 2013 |
| Couloir Property Development Ltd | Construction | 2014 |
| Coulson Homes Limited | Construction | 2006 |
| Coulson Macleod Limited | Administrative & support | 2003 |
| County Lifting Equipment (Holdings) Limited | Manufacturing | 1991 |
| County Lifting Services Limited | Construction | 1998 |
| Countywide Fire and Electrical Limited | Construction | 2020 |
| Cowern Holdings Ltd | Financial services | 2019 |
| Cowern Investments Ltd | Real estate | 2025 |
| CPD QA Limited | Administrative & support | 2014 |
| CPD Qualification STD. Ltd | Information & communication | 2016 |
| CPR Autoworks Ltd | Wholesale & retail | 2024 |
| Cpre Northamptonshire | Other services | 2005 |
| CR Pathways CIC | Health & social care | 2025 |
| CR Property Invest Ltd | Real estate | 2015 |
| CR Rooms Limited | Real estate | 2017 |
| CR01DH Ltd | Education | 2023 |
| CR7 Barbers Limited | Other services | 2024 |
| Cracking Investments Limited | Real estate | 2014 |
| Craig Mccallum Consulting Limited | Professional & scientific | 2025 |
| Cranfield Plasma Solutions Limited | Professional & scientific | 2019 |
| Cranford A.D. Limited | Energy | 2013 |
| Cranford Business Ltd | Professional & scientific | 2026 |
| Cranford Hall Limited | Real estate | 1947 |
| Cranford Management Limited | Real estate | 1968 |
| Cranford Power Limited | Energy | 2012 |
| Cranford Sport Horses Limited | Arts & recreation | 2021 |
| Cranford Tyre Recovery Limited | Water & waste | 2021 |
| Cranford UK Holdings Limited | Real estate | 2021 |
| Cransley Hospice Trust | Administrative & support | 2012 |
| Cransley Quality Fitting Services Limited | Construction | 2022 |
| Cransley Reservoir Wildlife Reserve CIC | Agriculture & fishing | 2022 |
| Craven Commerce Ltd | Wholesale & retail | 2025 |
| Crawford Assessors Limited | Professional & scientific | 2025 |
| Crawford Precision Engineering Limited | Manufacturing | 2005 |
| Crawford Precision Holdings Limited | Financial services | 2019 |
| Crawthorne Development BA Limited | Construction | 2017 |
| Creare J Design Limited | Professional & scientific | 2022 |
| Create.Nv Ltd | Manufacturing | 2024 |
| Creating Tomorrow College | Education | 2020 |
| Creating Tomorrow Multi Academy Trust | Education | 2015 |
| Creative Clout Ltd | Professional & scientific | 2025 |
| Creativity and Sense Limited | Administrative & support | 2009 |
| Creo Design & Developments Ltd | Construction | 2025 |
| Crest Microwave Limited | Other services | 2002 |