| Coquito UK Limited | Professional & scientific | 2024 |
| Coram Life Education Hillingdon Limited | Education | 1998 |
| Core Coding Limited | Information & communication | 2015 |
| Core Financial Management Ltd | Professional & scientific | 2015 |
| Core Outcome Limited | Information & communication | 2012 |
| Corel Works Consult Limited | Construction | 2024 |
| Coreonix Limited | Wholesale & retail | 2026 |
| Cornerstone Property Restorations Ltd | Real estate | 2026 |
| Cornwall Court (Uxbridge) Limited | Households | 2005 |
| Cornwall Road Management (Uxbridge) Limited | Households | 1989 |
| Cornwell Property Group Ltd | Construction | 2021 |
| Corporate Giftmedia Ltd | Wholesale & retail | 2024 |
| Corporate Synergy Solutions Ltd | Information & communication | 2014 |
| Corridy Property Management Limited | Real estate | 2017 |
| Cortex Couture Systems Ltd | Information & communication | 2026 |
| Cosmoed Limited | Wholesale & retail | 2021 |
| Cossio-Yates Consulting Ltd | Information & communication | 2026 |
| Costa Holdings Ltd | Professional & scientific | 2015 |
| Costa Investments Ltd | Wholesale & retail | 2022 |
| Costway Limited | Wholesale & retail | 2026 |
| Cotswold Court (High Wycombe) Management Company Limited | Real estate | 1989 |
| Counticare Limited | Other services | 1991 |
| County Hall Kingston Management Company Limited | Households | 2025 |
| Courier Consulting Ltd | Transport & logistics | 2020 |
| Court Theatre Training Company Ltd | Arts & recreation | 2011 |
| Courtlands Drive Blocks "E & F" Management Company Limited | Households | 1991 |
| Courtwood Finance Limited | Wholesale & retail | 1967 |
| Couture CLO Ltd | Wholesale & retail | 2024 |
| Cove Security Services Ltd | Administrative & support | 2026 |
| Coveberry Limited | Health & social care | 1975 |
| Covenco Ltd | Wholesale & retail | 1989 |
| COVENCO365 Limited | Information & communication | 1995 |
| Cover 4 Less Limited | Financial services | 2014 |
| Cover-More Insurance Services Ltd | Financial services | 1995 |
| Cowley Laundry Limited | Other services | 2013 |
| Cowley News London Ltd | Wholesale & retail | 2021 |
| CPR Investments Limited | Financial services | 2024 |
| Craft Carpentery Ltd | Construction | 2023 |
| Cranbourne Estates (Cornwall) Limited | Real estate | 2025 |
| Crane Market Insight Limited | Manufacturing | 2014 |
| Cranleigh Park Films Limited | Information & communication | 2024 |
| Cranmore Management Company Ltd | Households | 2026 |
| Craufurd Rise Residents Association Limited | Households | 1988 |
| Craven Keiller | Professional & scientific | 1986 |
| Cravenplan Computers Limited | Information & communication | 1984 |
| Crawley Grill Ltd | Hospitality | 2023 |
| Crea-Team BV Ltd | Wholesale & retail | 2022 |
| Create IT Limited | Information & communication | 2010 |
| Creative Fingers Community Nursery Ltd. | Education | 2013 |
| Creative Focus Ltd | Administrative & support | 2018 |
| Creative Personnel Limited | Professional & scientific | 1999 |
| Creatum Software Ltd | Information & communication | 2016 |
| Credipath Accountancy & Advisory Ltd | Professional & scientific | 2025 |
| Credipath Security Group Limited | Administrative & support | 2024 |
| Creditstream Trustees LLP | | 2018 |
| Creekwood Pharmaceuticals (UK) Ltd | Manufacturing | 2025 |
| Creighton Building Services Ltd | Construction | 2021 |
| Crep Junkie Limited | Arts & recreation | 2016 |
| Crescent Ltd | Other services | 2025 |
| Crew Barbers Ltd | Other services | 2025 |
| Crield House Management Limited | Households | 1986 |
| Crimscott Street, Bermondsey Management Company Limited | Real estate | 2017 |
| Cristian Development Ltd | Transport & logistics | 2018 |
| Cristiana Cleaning Limited | Administrative & support | 2026 |
| Critical Associates Ltd | Professional & scientific | 2017 |
| Criticare Experts Ltd | Health & social care | 2011 |
| Cromwell Property Limited | Real estate | 2026 |
| Cromwells Court Residents Limited | Real estate | 2003 |
| Crossgar Aviation Limited | Transport & logistics | 2021 |
| Crossroad Investment Limited | Real estate | 2025 |
| Crossway Deals Ltd | Wholesale & retail | 2021 |
| Crown Auto Rentals Ltd | Wholesale & retail | 2024 |
| Crown Bar & Banquet Limited | Hospitality | 2026 |
| Crown Properties (Hayes) Ltd | Real estate | 2022 |
| Crown Trichology Limited | Manufacturing | 2009 |
| Crownheights Limited | Real estate | 1996 |
| Crownline Management Ltd | Construction | 2026 |
| Crowther Court Biggleswade RTM Company Limited | Households | 2009 |
| CRS Convenience Ltd | Wholesale & retail | 2021 |
| CRS Estate Ltd | Wholesale & retail | 2022 |
| Crunchify Bites Limited | Hospitality | 2025 |
| Crust Dept. Limited | Hospitality | 2025 |
| Cruxed Ltd | Professional & scientific | 2025 |
| Cryptotip.Com Ltd | Information & communication | 2025 |
| Crystal Executive Cars Ltd | Transport & logistics | 2022 |
| Crystal Nail Saloon Ltd | Other services | 2021 |
| Crystal UK Services Ltd | Transport & logistics | 2018 |
| Crystal Wharf Management Company Limited | Households | 2003 |
| CSG Administration Ltd | Administrative & support | 2022 |
| CSG Property Investments Limited | Real estate | 2022 |
| CSM Render Masters Ltd | Construction | 2025 |
| Csst Group Ltd | Other services | 2018 |
| CT Property Ltd | Real estate | 2018 |
| Ctc-Anthonia Ltd | Transport & logistics | 2020 |
| CTD Group Holdings Ltd | Financial services | 2023 |
| CTD Investments Ltd | Real estate | 2022 |
| CTD Media Ltd | Information & communication | 2023 |
| CTD Systems Ltd | Manufacturing | 2022 |
| Cth-Digital LAB Limited | Information & communication | 2022 |
| CUBE3 Solutions Limited | Administrative & support | 2010 |