| Comar Mews (Cambridge) Management Limited | Real estate | 2015 |
| Comax Life Sciences Ltd | Professional & scientific | 2021 |
| Combinate Therapeutics Ltd | Professional & scientific | 2025 |
| Combinatorial Chemistry Solutions Limited | Manufacturing | 1998 |
| Combined Research Ltd | Information & communication | 2020 |
| Combo Drive Pictures Ltd. | Professional & scientific | 2014 |
| Comfort Labs Ltd | Wholesale & retail | 2022 |
| Comfortbloom Care & Support Ltd | Health & social care | 2026 |
| Comitpartners Limited | Information & communication | 2025 |
| Comma Studio Limited | Wholesale & retail | 2025 |
| Commercial Developments (Southampton) Limited | Construction | 1955 |
| Commited Care Ltd | Administrative & support | 2017 |
| Commodities Group Cambridge Limited | Wholesale & retail | 2018 |
| Common Marketing Limited | Professional & scientific | 2018 |
| Commonai C.I.C. | Information & communication | 2024 |
| Commonai Compute Ltd | Information & communication | 2024 |
| Commonwealth Argosy Foundation Ltd | Extraterritorial | 2014 |
| Commonwealth Chemistry | Professional & scientific | 2019 |
| Commonwealth Immigration Consultants Limited | Professional & scientific | 2000 |
| Commsonic Ltd. | Information & communication | 2000 |
| Commtech (Europe) Limited | Construction | 2014 |
| Commtech Rose Limited | Construction | 2016 |
| Communigage Ltd | Professional & scientific | 2023 |
| Community Sparx CIC | Information & communication | 2018 |
| Community Through Martial Arts Ltd | Arts & recreation | 2011 |
| Communiwit UK Ltd | Information & communication | 2026 |
| Commuter Games Limited | Information & communication | 2022 |
| Comp Plus Ltd | Professional & scientific | 2026 |
| Company 57 Limited | Information & communication | 2024 |
| Companydeep Ltd | Information & communication | 2017 |
| Compass Developments (Cambridge) Limited | Construction | 2018 |
| Compass Educational Consultancy Limited | Education | 2003 |
| Compass Finance Claims Limited | Extraterritorial | 2010 |
| Compass Global Events Limited | Real estate | 2016 |
| Compass Industrial Supply Chain Ltd. | Manufacturing | 2024 |
| Compass IP Ltd | Professional & scientific | 2021 |
| Compassionate Heart Ltd | Other services | 2012 |
| Compchem Solutions Limited | Professional & scientific | 2014 |
| Complete Cleaning Management Limited | Administrative & support | 2013 |
| Complete Cleaning Services Cambs Limited | Administrative & support | 2019 |
| Complete Construction (Cambridge) Ltd | Construction | 2022 |
| Complete Electrical Solutions (East Anglia) Ltd | Construction | 2012 |
| Complete Fabrication Ltd | Manufacturing | 1998 |
| Complete Feet Podiatry Limited | Health & social care | 2017 |
| Complete Labs Ltd | Information & communication | 2022 |
| Complete Management Solutions Ltd | Administrative & support | 2011 |
| Complete Planned Maintenance Limited | Energy | 1996 |
| Complete Support Worker UK Ltd | Health & social care | 2020 |
| Complete Unity Yoga Ltd | Wholesale & retail | 2018 |
| Complex Systems Research Limited | Professional & scientific | 2005 |
| Compliance Bridge International Ltd | Professional & scientific | 2024 |
| Compliance Training Products Limited | Information & communication | 2002 |
| Composite Designers Ltd | Manufacturing | 2019 |
| Composite Engineering Dietrich Ltd | Manufacturing | 2024 |
| Composite Tooling & Structures Ltd | Manufacturing | 2018 |
| Composites ARG Ltd | Manufacturing | 2023 |
| Compossible Umwelten Ltd | Manufacturing | 2026 |
| Comprehensive Removals & Storage Limited | Transport & logistics | 2020 |
| Compserve Limited | Wholesale & retail | 1970 |
| Compton & Casburn Limited | Construction | 2007 |
| Compton & Parkinson Limited | Construction | 2008 |
| Compton Heights (Wootton Bassett) Management Company Limited | Households | 2003 |
| Computational Modelling Cambridge Limited | Information & communication | 2008 |
| Computer & Communications Co. Limited | Information & communication | 1990 |
| Computer Resource SS Ltd | Information & communication | 2015 |
| Computers Madeasy Ltd | Information & communication | 2002 |
| Computing Distribution Group Ltd | Information & communication | 2008 |
| Comsol Limited | Information & communication | 2001 |
| Comvic Ltd | Manufacturing | 2025 |
| Conceptual Networks Limited | Administrative & support | 2002 |
| Concerthotels Limited | Administrative & support | 2007 |
| Concierge Cambridge Ltd | Administrative & support | 2020 |
| Concord Close Management Company Limited | Households | 1983 |
| Concorde Aerospace Solutions Ltd | Other services | 2016 |
| Concordia NET, Inc. | | 2000 |
| Conference Cambridge Limited | Extraterritorial | 2008 |
| Confi-Dent Aesthetix Limited | Health & social care | 2021 |
| Confinis (UK) Ltd | Professional & scientific | 2024 |
| Confluctuo Limited | Professional & scientific | 2017 |
| Conformiflux Ltd | Professional & scientific | 2025 |
| Congenica Ltd | Professional & scientific | 2012 |
| Conington Building Consultants Limited | Construction | 2020 |
| Conington Farms Limited | Agriculture & fishing | 1954 |
| Conla Trading Limited | Wholesale & retail | 2025 |
| Connect Cambridge Ltd | Transport & logistics | 2025 |
| Connect Import and Export Co., Ltd | Wholesale & retail | 2024 |
| Connectbatch Limited | Information & communication | 2015 |
| Connectopia Entertainment Ltd | Information & communication | 2025 |
| Conosco Property Partnership LLP | | 2013 |
| Conscious & Calm CIC | Health & social care | 2024 |
| Conscious Cambridge Ltd | Administrative & support | 2022 |
| Conscious Communications Ltd | Administrative & support | 2008 |
| Conscious Entrepreneurs Ltd | Professional & scientific | 2025 |
| Consignify Ltd | Information & communication | 2025 |
| Consilient Ltd | Professional & scientific | 2003 |
| Consolidated Retailers Limited | Wholesale & retail | 2015 |
| Consolidocs Limited | Information & communication | 2020 |
| Consort Strategy Ltd | Professional & scientific | 2016 |
| Constant Cooling Limited | Energy | 1991 |
| Constantanalyst.Com Ltd | Administrative & support | 2025 |