| Clay Pigeon Essex Limited | Wholesale & retail | 2023 |
| Clay Street Project Limited | Real estate | 2012 |
| Claydons Consulting Limited | Professional & scientific | 2004 |
| Clayton Family Holdings Ltd | Real estate | 2024 |
| Clean Drain Limited | Water & waste | 1980 |
| Clean&Fresh Housekeeping Limited | Households | 2022 |
| Clean&Shine Cleaning Ltd | Administrative & support | 2026 |
| Cleaning Matters Limited | Administrative & support | 2000 |
| Cleaning System Ltd | Wholesale & retail | 2016 |
| Cleanpod Limited | Wholesale & retail | 2020 |
| Clear Brew Chelmsford Limited | Administrative & support | 2022 |
| Clear Horizon Joint Ventures Ltd | Real estate | 2017 |
| Clear Horizon Lettings Ltd | Real estate | 2024 |
| Clear Horizon Property Group Ltd | Real estate | 2019 |
| Clear Mission Limited | Other services | 2022 |
| Clear N Company Ltd | Wholesale & retail | 2023 |
| Clear Therapies Lodge Ltd | Hospitality | 2019 |
| Clear Therapies Ltd | Health & social care | 2016 |
| Clear View Hotels Limited | Construction | 1936 |
| Clear-Matics Ltd | Construction | 2014 |
| Clearbenchmark Ltd | Information & communication | 2020 |
| Clearline Associates Ltd | Real estate | 2014 |
| Clearline PHD Holdings Limited | Financial services | 2022 |
| Clearline Plumbing Heating & Drainage Limited | Administrative & support | 2014 |
| Clearstone Services SH UK Limited | Other services | 2018 |
| Clearview Communications Holdings Ltd | Financial services | 2021 |
| Clearview Improvements Ltd | Construction | 2017 |
| Clearview Media Ltd | Extraterritorial | 2014 |
| Clearvision (Essex) Limited | Professional & scientific | 2009 |
| Clegg Enterprises Ltd | Professional & scientific | 2008 |
| Clementine Management Group Limited | Real estate | 2019 |
| Clements Green (South Woodham Ferrers) Management Company Limited | Households | 1983 |
| CLG Cricgear Ltd | Wholesale & retail | 2025 |
| Clhk Limited | Real estate | 2022 |
| Clifford's WM Limited | Water & waste | 2003 |
| Cliffords Leisure Limited | Arts & recreation | 1999 |
| Cliffords Limited | Professional & scientific | 1972 |
| Climping International Limited | Professional & scientific | 2017 |
| CLINEY67 Limited | Professional & scientific | 2020 |
| Clinic Plus Chelmsford Limited | Wholesale & retail | 2025 |
| Clinic Plus Edgware Limited | Wholesale & retail | 2025 |
| Clinic Plus Limited | Wholesale & retail | 2025 |
| Clinical Time Freedom Limited | Administrative & support | 2025 |
| Clinical Waste Disposal Limited | Administrative & support | 2019 |
| Clip Meats Limited | Wholesale & retail | 2016 |
| Clixx Media Ltd | Professional & scientific | 2023 |
| CLL Group Holdings Limited | Professional & scientific | 2021 |
| CLM Accounting Ltd | Professional & scientific | 2025 |
| CLM Training and Consultancy Ltd | Professional & scientific | 2026 |
| Clockhouse Road Management Ltd | Households | 2011 |
| Clockhouse Solutions Ltd | Information & communication | 2023 |
| Clockwork Despatch Limited | Real estate | 2019 |
| Clockwork Logistics Limited | Transport & logistics | 2019 |
| Clomotion Limited | Information & communication | 2015 |
| Closelink Limited | Real estate | 2002 |
| Clotta Limited | Extraterritorial | 2023 |
| Clottergate Associates Limited | Administrative & support | 2011 |
| Cloud 9 Sports Limited | Arts & recreation | 2016 |
| Cloud Professor Ltd | Wholesale & retail | 2017 |
| Cloudarc Solutions Ltd. | Information & communication | 2015 |
| Cloudesley Capital Limited | Real estate | 2022 |
| Cloudfirst Technologies Ltd | Information & communication | 2017 |
| Cloudtec 32 Limited | Information & communication | 2020 |
| Clover Nursery School Limited | Education | 2023 |
| Clover Services Limited | Administrative & support | 2008 |
| Clune Court (Shenfield) Management Limited | Households | 1990 |
| CLZ Hospitality Limited | Hospitality | 2026 |
| CM China Kitchen Limited | Hospitality | 2024 |
| CM City Limited | Hospitality | 2024 |
| CM Data Management Services Ltd | Information & communication | 2012 |
| CM Dave Limited | Administrative & support | 2022 |
| CM Express Ltd | Information & communication | 2025 |
| CM Kitchens Limited | Construction | 2026 |
| CM Nutrition Limited | Health & social care | 2025 |
| CM Removals & Storage Ltd | Transport & logistics | 2026 |
| CM Rental Properties Ltd | Real estate | 2018 |
| CM1 13 Limited | Wholesale & retail | 2026 |
| CM1 8 Limited | Wholesale & retail | 2026 |
| CM1 Logistics Ltd | Transport & logistics | 2020 |
| CM1 Plumbing and Heating Ltd | Construction | 2019 |
| CM1 Property Maintenance Ltd | Administrative & support | 2017 |
| CM1 Valet Ltd | Wholesale & retail | 2024 |
| CM2 10 Limited | Wholesale & retail | 2026 |
| CM2 Consultancy Limited | Administrative & support | 2024 |
| CM2 Legal Consultancy Limited | Professional & scientific | 2025 |
| CM3 Consultancy Limited | Professional & scientific | 2024 |
| CM3 Marine Consultancy and Projects LLP | | 2011 |
| CM3 Services Limited | Construction | 2022 |
| CME Consultancy Ltd | Financial services | 2026 |
| CMH Management Limited | Real estate | 1965 |
| CMH Psychology Services Ltd | Education | 2024 |
| CMP Lucidity Limited | Professional & scientific | 2024 |
| Cmventilation Services Ltd | Construction | 2024 |
| CMW Pathology Limited | Health & social care | 2022 |
| Cmxf Limited | Hospitality | 2022 |
| CN 90'S Beauty Limited | Other services | 2024 |
| CN Studio Ltd | Information & communication | 2012 |
| CNC Cutting Essex Ltd | Manufacturing | 2015 |
| CNR Studio Ltd | Professional & scientific | 2025 |
| CNT Clinic Ltd | Other services | 2022 |