| City Supermarket (London) Limited | Wholesale & retail | 2006 |
| City Tax London Limited | Professional & scientific | 2015 |
| Citylink Haulage Ltd | Transport & logistics | 2023 |
| Citymoor Ltd | Real estate | 2019 |
| Citywid Limited | Wholesale & retail | 2026 |
| Civico Consultants Ltd | Professional & scientific | 2019 |
| CK Collection Limited | Wholesale & retail | 2013 |
| CK Fashions Limited | Wholesale & retail | 2006 |
| Ckreative Events Limited | Hospitality | 2014 |
| Clareo Limited | Information & communication | 1998 |
| Classic Aura Traders Limited | Wholesale & retail | 2026 |
| Classic Kitchen Foods Ltd | Hospitality | 2025 |
| Classic Plaster Artistry Ltd | Construction | 2025 |
| Classy Boutique Limited | Wholesale & retail | 2016 |
| Classy Crude Ltd | Wholesale & retail | 2025 |
| Clean and Move Ltd | Administrative & support | 2025 |
| Cleaning Clowns Limited | Administrative & support | 2023 |
| Cleanmatch Ltd | Administrative & support | 2025 |
| Clear Innovation Solutions Limited | Wholesale & retail | 2025 |
| Clear Roots Limited | Education | 2025 |
| Clear Stone Construction Ltd | Construction | 2022 |
| Clearcons Limited | Information & communication | 2026 |
| Clearmove Property Investment Ltd | Households | 2019 |
| Clearpath Global Education Ltd | Education | 2026 |
| Cleethorpes Property Ltd | Real estate | 2026 |
| Cleethorpes Surgery Ltd | Health & social care | 2026 |
| Clewis Properties Ltd | Real estate | 2021 |
| Click N Collect Ltd | Wholesale & retail | 2025 |
| Clifton UK Holdings Ltd | Financial services | 2026 |
| Clinical Consultants Limited | Professional & scientific | 2012 |
| CLK Trade Limited | Wholesale & retail | 2025 |
| Clock House Retail Limited | Real estate | 2007 |
| Clock Tower Smile Ltd | Real estate | 2020 |
| Clogzilla Plumbing and Drainage Ltd | Construction | 2025 |
| Clothing Spark Limited | Hospitality | 2018 |
| Clothiyo Ltd | Wholesale & retail | 2021 |
| Cloud Flow Distribution Ltd | Wholesale & retail | 2025 |
| Cloud Hire Ltd | Construction | 2025 |
| Cloud Travel Limited | Administrative & support | 2015 |
| Cloud Visa Limited | Administrative & support | 2017 |
| Cloudsync Digital Ltd | Wholesale & retail | 2025 |
| CM Assets & Investments Ltd | Real estate | 2025 |
| CM Traders Limited | Administrative & support | 2026 |
| CMM Constructions Ltd | Construction | 2019 |
| CMN Tiling Limited | Construction | 2017 |
| Coalyard Barbeque Limited | Hospitality | 2019 |
| Code Expeditions Ltd | Information & communication | 2024 |
| Cogent Project Services Ltd | Professional & scientific | 2012 |
| Colnbrook Heights Limited | Real estate | 2021 |
| Colnbrook Proprietors Limited | Real estate | 2025 |
| Colors Enterprises C.I.C. | Health & social care | 2013 |
| Colour Care KIT Ltd | Wholesale & retail | 2020 |
| Colours Textile Ltd | Wholesale & retail | 2024 |
| Colwick Business Park Limited | Real estate | 2023 |
| Comer Crescent RTM Ltd | Real estate | 2018 |
| Comfort Car Hire Ltd | Wholesale & retail | 2025 |
| Comfort Climate Limited | Transport & logistics | 2025 |
| Comfort Construction Services Ltd | Construction | 2025 |
| Comfort Homes London Limited | Real estate | 2017 |
| Committee - the Community Loan Company Ltd | Financial services | 2018 |
| Commonwealth Consultancy Services Ltd | Professional & scientific | 1998 |
| COMMUNITIES4CHANGE C.I.C. | Health & social care | 2008 |
| Company Financial Accountants Limited | Professional & scientific | 2007 |
| Competitive Security Services Limited | Professional & scientific | 2014 |
| Compralo Limited | Wholesale & retail | 2025 |
| Compuglobuk Limited | Information & communication | 2019 |
| Concept Technical Ltd | Professional & scientific | 2005 |
| Conjugate Limited | Information & communication | 2017 |
| CONNECT22 Consultancy Limited | Transport & logistics | 2017 |
| Connectcarehub Ltd | Education | 2026 |
| Connectels Ltd | Wholesale & retail | 2025 |
| Connoisseur Recovery Limited | Transport & logistics | 2004 |
| Construction Space Limited | Construction | 2019 |
| Content Holdings Limited | Financial services | 2022 |
| Contract Beds Holdings Limited | Other services | 2018 |
| Contract Beds Ltd | Real estate | 2012 |
| Contrangeuk Ltd | Professional & scientific | 2025 |
| Conway Roofing & Building Ltd | Construction | 2022 |
| Coolfreeze Foodservices Limited | Hospitality | 2015 |
| Coracho Limited | Administrative & support | 2022 |
| Coral Investments Limited | Real estate | 2014 |
| Cordial Transport Ltd | Transport & logistics | 2021 |
| Corporate Affairs Handling Limited | Administrative & support | 1998 |
| Corporate Hippy House Holdings Ltd | Information & communication | 2020 |
| Corporate Hippy House Ltd | Information & communication | 2017 |
| Cosmic Football Ltd | Arts & recreation | 2025 |
| Cosmic Tutors Ltd | Education | 2024 |
| Cosmicalt Ltd | Wholesale & retail | 2025 |
| Cosmicuk Ltd | Wholesale & retail | 2022 |
| Costcutter Food & Wine Limited | Wholesale & retail | 2016 |
| Costel M Ltd | Construction | 2025 |
| Cotton Life Textile Ltd | Wholesale & retail | 2022 |
| Countech Computer Systems Limited | Information & communication | 1989 |
| Countryman Express Couriers Ltd | Transport & logistics | 2020 |
| Courier City Ltd | Transport & logistics | 2019 |
| Covi Ltd | Construction | 2023 |
| Cozee Care Homes Limited | Health & social care | 1995 |
| Cozmotech Ltd | Wholesale & retail | 2022 |
| Cozy House Heating Limited | Construction | 2026 |
| Cozy Sleep Ltd | Hospitality | 2025 |