| Complete Resolve Ltd | Construction | 2018 |
| Compumex Limited | Information & communication | 2025 |
| Comtutor Ltd. | Information & communication | 1997 |
| Conceptualise Limited | Professional & scientific | 2004 |
| Concrete Pump Hire Ltd | Administrative & support | 2013 |
| Concrete Sales Ltd | Manufacturing | 2016 |
| Conferio Limited | Information & communication | 2005 |
| Conifer Close Management Company Limited | Households | 1993 |
| Conifer Data Ltd | Professional & scientific | 2013 |
| Conifercourt (Building) Limited | Construction | 1977 |
| Conifercourt Holdings Limited | Construction | 1987 |
| Conifercourt Leisure Limited | Arts & recreation | 1985 |
| Conifercourt Limited | Real estate | 1972 |
| Connaught Gardens (Muswell Hill) Management Limited | Households | 2023 |
| Connect Contractors Limited | Construction | 2024 |
| Connect Express Consultants Limited | Administrative & support | 1997 |
| Connect Home Tech Ltd | Construction | 2012 |
| Connected by Data Ltd | Professional & scientific | 2022 |
| Connected International Education Ltd | Education | 2023 |
| Connections in Mind C.I.C. | Education | 2016 |
| Connectus Capital Advisors Ltd | Professional & scientific | 2024 |
| Conseal Security Ltd | Information & communication | 2005 |
| Conservatory Blinds Ltd | Extraterritorial | 2022 |
| Constable Digital Ltd | Professional & scientific | 2013 |
| Construct and Extend Ltd | Construction | 2025 |
| Construction Rigging Ltd | Administrative & support | 2019 |
| Consult 14 Limited | Information & communication | 2019 |
| Consult People Limited | Professional & scientific | 2006 |
| Consultant Anaesthetist Ltd | Health & social care | 2013 |
| Consulting Services POD Ltd | Professional & scientific | 2018 |
| Contact Continuous Limited | Manufacturing | 1985 |
| Content Incorporated Ltd | Administrative & support | 2015 |
| Contessa Consulting Ltd | Professional & scientific | 2019 |
| Contract Design Service Limited | Construction | 2016 |
| Contractors Emea Ltd | Information & communication | 2024 |
| Controlsense Limited | Construction | 1998 |
| Convenient Living Ltd | Real estate | 2017 |
| Cooper Refurbishments Limited | Construction | 2007 |
| Coops Brokers Limited | Financial services | 2013 |
| Copacetic Media Limited | Information & communication | 2025 |
| Copley Tech Limited | Financial services | 2023 |
| Copper Beech Management Company Epsom Ltd | Households | 2017 |
| Copper Seas Training Consultancy Limited | Professional & scientific | 2014 |
| Copperfield Court Freehold (Leatherhead) Limited | Households | 2016 |
| Copperfield Court Management Limited | Households | 1972 |
| Copperhouse Plumbing & Heating Ltd | Construction | 2012 |
| Copse Management Limited(The) | Other services | 1986 |
| Copsem Way (Esher) Management Company Limited | Households | 1989 |
| Corbie Products Ltd | Manufacturing | 2017 |
| Corby Healthcare Limited | Health & social care | 2003 |
| Corby Tennis Limited | Arts & recreation | 1991 |
| Core Build Services Ltd | Professional & scientific | 2025 |
| Core Tech TV Ltd | Administrative & support | 2016 |
| Corner Farm Close Management Limited | Households | 1998 |
| Cornercroft Management Company Limited | Households | 1994 |
| Cornerstones Limited | Professional & scientific | 2000 |
| Corporate & Community Development Ltd | Administrative & support | 2011 |
| Corrick, Wales & Partners LLP | | 2017 |
| Cortes Limited | Manufacturing | 1993 |
| Coskry Holdings Ltd | Extraterritorial | 2020 |
| Cosmetic, Toiletry & Perfumery Foundation | Health & social care | 1993 |
| Cosmomate (UK) Limited | Financial services | 1988 |
| Costello Ventures Ltd | Other services | 2013 |
| Cote Meridian Consultants Limited | Professional & scientific | 2026 |
| Cotterill & Sons Limited | Information & communication | 2017 |
| Cotyledon Gardens Ltd | Administrative & support | 2021 |
| County Consulting Ltd | Other services | 1997 |
| Court Lodge Epsom Limited | Real estate | 2014 |
| Court on Camera Limited | Other services | 2003 |
| Court Security Limited | Wholesale & retail | 1996 |
| Courtney Electrical (Surrey) Limited | Construction | 2019 |
| Covent Garden Plants and Pots Limited | Wholesale & retail | 2026 |
| Covered Bridges Hospitality Ltd | Hospitality | 2021 |
| Covered Property Services Ltd | Real estate | 2024 |
| Covert Songs Ltd | Information & communication | 2012 |
| Coyle Eastfield Limited | Financial services | 2025 |
| Coyle Limited | Financial services | 2018 |
| Cozy Bars Limited | Hospitality | 2024 |
| Cozy Pods Ltd | Real estate | 2024 |
| CPD Health Courses UK Limited | Education | 2020 |
| Cpdc Limited | Wholesale & retail | 2013 |
| CPH Accountancy Ltd | Extraterritorial | 2012 |
| CPW Marine Ltd | Professional & scientific | 2021 |
| Crab UK Property Holdings Limited | Real estate | 2024 |
| Craig Broughton Limited | Construction | 2007 |
| Cralo Limited | Construction | 2026 |
| Crane Construction Consultancy Limited | Construction | 2013 |
| Crashmaths Limited | Information & communication | 2017 |
| Crawford & Co Scaffolding Limited | Construction | 2013 |
| Crawford Services Ltd | Information & communication | 2019 |
| Create Editorial Consultants Ltd | Information & communication | 2011 |
| Create Outlines Ltd | Professional & scientific | 2021 |
| Creation Architects Limited | Professional & scientific | 2011 |
| Creative Video Solutions Ltd | Information & communication | 2014 |
| Creativeunix Limited | Information & communication | 2023 |
| Crebinick House Ltd | Hospitality | 2024 |
| Credit UK Limited | Financial services | 2002 |
| Cresthill (UK) Limited | Professional & scientific | 2014 |
| Cresthill Capital Limited | Real estate | 2014 |
| Crestline Group Ltd | Wholesale & retail | 2025 |