| Chughtai Educational Excellence Limited | Education | 2025 |
| Chukaz Care Ltd | Health & social care | 2017 |
| Chunk Management Ltd | Professional & scientific | 2016 |
| Church Close Properties Limited | Real estate | 2021 |
| Church Farm Close Management Ltd | Real estate | 2019 |
| Church Meadow (Sproughton) Management Company Limited | Households | 2018 |
| Church Mews (Tiptree) Limited | Households | 2008 |
| Church Street Townhouse Ltd | Hospitality | 2013 |
| Churchfield Business Brokers Ltd | Professional & scientific | 2003 |
| Churchill Brothers Limited | Manufacturing | 2006 |
| Churchill Digital Consultancy Limited | Information & communication | 2019 |
| Churchill Road (Freehold) Ltd | Extraterritorial | 2012 |
| Churchmic Security Services Ltd | Administrative & support | 2024 |
| Churchway Projects Ltd | Real estate | 2025 |
| Ciac Fulfilment Limited | Transport & logistics | 2020 |
| Cignia Consulting Limited | Other services | 2013 |
| Cignia Franchise Limited | Hospitality | 2025 |
| Cignia Holdings Limited | Administrative & support | 2017 |
| Cignia Property Limited | Real estate | 2018 |
| Cikizwa Ltd | Other services | 2025 |
| Cineimage Ltd | Information & communication | 2011 |
| Cinema Luxe Contracts Ltd | Extraterritorial | 2023 |
| Cinema Luxe Ltd | Professional & scientific | 2018 |
| Cinko UK Limited | Wholesale & retail | 2017 |
| Cinnamon Brown Limited | Hospitality | 2005 |
| Cintri Ltd | Administrative & support | 2015 |
| Circa 42 Limited | Wholesale & retail | 1999 |
| Circle Drive Ltd | Other services | 2024 |
| Circle Green Limited | Information & communication | 2019 |
| Citadel of Grace Ltd | Other services | 2025 |
| Citizens Advice Colchester | Professional & scientific | 2002 |
| City Brewery Sporting Events Limited | Professional & scientific | 2018 |
| City Career LAB Ltd | Professional & scientific | 2020 |
| City Clinic Plymouth Ltd | Health & social care | 2026 |
| City Compliance-Uk Limited | Energy | 2023 |
| City Decorators Limited | Construction | 2011 |
| City Fire Training Ltd | Public administration | 2009 |
| City M&E Ltd | Construction | 2017 |
| City of Grace and Peace Properties Ltd | Construction | 2026 |
| City Roofscapes Limited | Construction | 2021 |
| City Silence Ltd | Wholesale & retail | 2018 |
| City Tax Accountancy Solutions Limited | Professional & scientific | 2022 |
| City to Country Retreat Limited | Hospitality | 2021 |
| Citygrove Developments Limited | Wholesale & retail | 2012 |
| Cityline Taxis EN Limited | Transport & logistics | 2026 |
| Cityspace Lets Ltd | Hospitality | 2019 |
| CJ & DJ Barton Limited | Manufacturing | 2005 |
| CJ Connects Ltd | Professional & scientific | 2025 |
| CJ Creates Limited | Professional & scientific | 2021 |
| CJ Property 2025 Ltd | Real estate | 2025 |
| CJ Wood Plant Hire Limited | Construction | 2014 |
| CJ11CEN Ltd | Transport & logistics | 2019 |
| CJA Advisory Limited | Professional & scientific | 2026 |
| CJC BD Consultancy Ltd | Administrative & support | 2026 |
| CJC Contracts Ltd | Construction | 2007 |
| CJD Electrical Ltd | Construction | 2015 |
| CJD Louvres Limited | Construction | 2009 |
| CJL Contracts Limited | Administrative & support | 2016 |
| CJL Housing Limited | Real estate | 2020 |
| CJM Investigations Limited | Administrative & support | 2013 |
| CJM Media Ltd | Information & communication | 2016 |
| CJO Plumbing & Heating Ltd | Construction | 2018 |
| Cjrail Ltd | Construction | 2023 |
| CJS CNC Machining Limited | Professional & scientific | 2007 |
| CJS Painting Solutions Limited | Construction | 2021 |
| CK Digital Solutions Ltd | Information & communication | 2020 |
| CK Family Limited | Administrative & support | 2014 |
| CK98 Ltd | Professional & scientific | 2023 |
| CKD Property Maintenance Ltd | Construction | 2025 |
| Ckdc Enterprise Ltd | Wholesale & retail | 2017 |
| Ckhkeng Ltd | Professional & scientific | 2025 |
| CKJ Services Limited | Construction | 2017 |
| CKM Care Ltd | Administrative & support | 2020 |
| CKR Investment Management Ltd | Financial services | 2009 |
| CL Construction Ltd | Construction | 2021 |
| CL24 Ltd | Real estate | 2023 |
| Clacton DRY Cleaners Ltd | Other services | 2022 |
| Clacton Osteopathy & Physiotherapy Clinic Ltd | Health & social care | 2022 |
| Clacton Wellbeing Centre Limited | Extraterritorial | 2018 |
| Claims East Limited | Other services | 2025 |
| Claimsforce Ltd | Financial services | 2016 |
| Claire Court Management (West Mersea) Limited | Households | 1990 |
| Claire Pemrick Ltd | Health & social care | 2025 |
| Clams Consulting Limited | Information & communication | 2018 |
| Clams Property Group Limited | Professional & scientific | 2018 |
| Clandel Global Concept Limited | Wholesale & retail | 2024 |
| Clara Commerce Limited | Information & communication | 2026 |
| Clare Heyes & Co Ltd | Professional & scientific | 2020 |
| Clare HR Consultancy Limited | Administrative & support | 2019 |
| Clareanne Ltd | Real estate | 2021 |
| Claremont Heights 1-72 RTM Company Limited | Households | 2009 |
| Claremont Heights 73-162 RTM Company Limited | Households | 2009 |
| Clarix Services & Consulting Ltd | Professional & scientific | 2026 |
| Clarke & Walden Properties Ltd | Real estate | 2021 |
| Clarke and SON Builders Limited | Extraterritorial | 2012 |
| Clarks Endeavour Limited | Wholesale & retail | 2022 |
| Clartes Ltd | Manufacturing | 2010 |
| Class Cleaning Solutions Limited | Administrative & support | 2022 |
| Classic and Retro Limited | Manufacturing | 2012 |
| Classic Car Paint Ltd | Wholesale & retail | 2020 |