| Cross World Solutions UK Ltd | Wholesale & retail | 2025 |
| Cross-Border Tax Solutions Limited | Professional & scientific | 2012 |
| Cross-Point Global Resources Ltd | Administrative & support | 2016 |
| Crossfit Colchester Ltd | Arts & recreation | 2013 |
| Crossfit Direwolf Ltd | Arts & recreation | 2020 |
| Crosslight & Sound Production Services Limited | Professional & scientific | 2018 |
| Crossways (Little Clacton) Management Ltd | Households | 2024 |
| Crossways Holdings Ltd | Real estate | 2018 |
| Crosswinds Investments Limited | Real estate | 2009 |
| Crouch Street Hair & Beauty Salon Limited | Other services | 2004 |
| Crouch Valley Vineyards Association Limited | Other services | 2023 |
| Crouchfields Works Limited | Administrative & support | 2012 |
| Croud Limited | Professional & scientific | 2022 |
| Crow-Over-Ther Records Ltd | Information & communication | 2014 |
| Crowborough Legacy Limited | Construction | 2022 |
| Crowchoir Ltd | Wholesale & retail | 2025 |
| Crowe (Essex) Holdings Limited | Administrative & support | 2020 |
| Crowley Solutions Ltd | Information & communication | 2022 |
| Crown & Glory Beauty Salon Ltd | Other services | 2025 |
| Crown Compost & Waste Management Limited | Agriculture & fishing | 2024 |
| Crown Consultancy Ltd | Extraterritorial | 2010 |
| Crown Inn Management Limited | Hospitality | 2024 |
| Crown Insurance Consultancy Ltd | Financial services | 2007 |
| Crown Legal Consultancy Ltd | Professional & scientific | 2008 |
| Crown Planning Ltd | Construction | 2022 |
| Crown Reinsurance Consultancy Ltd | Financial services | 2007 |
| Crown Street Freehold Limited | Real estate | 2022 |
| Crown Ventilation Holdings Limited | Administrative & support | 2021 |
| Crown Weddings & Marquee Hire Ltd | Hospitality | 2016 |
| Crowncouture Limited | Wholesale & retail | 2022 |
| Crowther Nurseries Ltd. | Wholesale & retail | 1977 |
| CRU KIT Ltd | Wholesale & retail | 2023 |
| Cruise Dialysis Limited | Administrative & support | 2015 |
| Cruise Miles Limited | Extraterritorial | 2011 |
| Crush Your Competition Ltd | Information & communication | 2022 |
| Crushbyte Ltd | Administrative & support | 2014 |
| Crusher Contracting UK Limited | Construction | 2018 |
| Cruspane Limited | Real estate | 1976 |
| Crystal Cleaning Service Limited | Other services | 2012 |
| Crystal Cleaning Solutions Ltd | Administrative & support | 2025 |
| Crystal Clear Hygiene Limited | Administrative & support | 2013 |
| Crystal Clear Products (2000) Ltd | Water & waste | 1999 |
| Crystal Fortress Shelves Ltd | Wholesale & retail | 2024 |
| Crystal Jumeriah Ltd | Wholesale & retail | 2023 |
| Crystal Restaurant Essex Ltd | Hospitality | 2025 |
| Crystal Wave Limited | Other services | 2024 |
| Crystallise Limited | Health & social care | 2012 |
| CS Automotive Repair Ltd | Wholesale & retail | 2024 |
| CS Engineering Essex Ltd | Manufacturing | 2017 |
| CS Estate & Property Management Limited | Real estate | 2016 |
| CS Holdings (Colchester) Ltd | Financial services | 2021 |
| CS Legacy Limited | Construction | 2022 |
| CS Training Solutions Ltd | Professional & scientific | 2025 |
| CSB Aesthetics Ltd | Other services | 2026 |
| CSH Brickwork Ltd | Construction | 2023 |
| CSH Environmental Limited | Water & waste | 1998 |
| CSH Limited | Professional & scientific | 2002 |
| CSH Recycling Limited | Extraterritorial | 2009 |
| CSN Consultancy C.I.C. | Professional & scientific | 1993 |
| Csquared-Maritime Ltd | Professional & scientific | 2025 |
| CSR Construction Ltd | Construction | 2018 |
| CT24 Limited | Wholesale & retail | 2015 |
| CTB Property Solutions Ltd | Wholesale & retail | 2025 |
| CTC Retail Ltd | Wholesale & retail | 2024 |
| CTM Contracting Ltd | Administrative & support | 2019 |
| CTM Groundworks Ltd | Construction | 2025 |
| Ctsc Limited | Wholesale & retail | 2023 |
| Cubbit Properties Ltd | Administrative & support | 2024 |
| Cube 1994 Ltd | Administrative & support | 2010 |
| Cube Maintenance 1994 Ltd | Wholesale & retail | 2025 |
| CUBE6 Limited | Manufacturing | 2005 |
| Cubit Engineering Consultants Ltd | Professional & scientific | 2023 |
| Cuckoo Dough Restaurants Ltd | Hospitality | 2024 |
| Cuckoo Farm Studios Limited | Arts & recreation | 2008 |
| Cuckoo Point Management Limited | Households | 2007 |
| Cudl Ltd | Wholesale & retail | 2025 |
| Cudmore Storage Limited | Transport & logistics | 2025 |
| Cumora Healthcare Ltd | Health & social care | 2025 |
| Cupsdirect Limited | Wholesale & retail | 2010 |
| Cura Energy Limited | Administrative & support | 2011 |
| Curio Labs Limited | Information & communication | 2016 |
| Curious Infuser Ltd | Wholesale & retail | 2025 |
| Curis Consultancy & Case Management Ltd | Information & communication | 2020 |
| Curlew Properties Limited | Households | 1985 |
| Curnow Soper Consultancy Limited | Professional & scientific | 2022 |
| Currell Holdings Limited | Financial services | 2026 |
| Curtis & Edwards Limited | Wholesale & retail | 2025 |
| Curtis Assemble and Test Limited | Manufacturing | 1999 |
| Curtis Carpentry Limited | Construction | 1997 |
| Curtis Machine Tools Limited | Manufacturing | 1999 |
| Curtis Plumbing Ltd | Construction | 2014 |
| Curzon DE Vere Limited | Administrative & support | 2012 |
| Curzon Mill Developments Ltd | Administrative & support | 2019 |
| Custodire Risk Management Limited | Professional & scientific | 2023 |
| CUT and Style Ltd | Other services | 2018 |
| Cutright Ltd | Other services | 2020 |
| Cutting AM Limited | Real estate | 2023 |
| Cutting Edge Construction & Carpentry Ltd | Construction | 2022 |
| CV Diagnostics Limited | Health & social care | 2024 |
| CVC Developments Ltd | Households | 2020 |