| Cargo CAB Ltd | Transport & logistics | 2017 |
| Caring Direct Ltd | Health & social care | 2009 |
| Carlytical Ltd | Wholesale & retail | 2020 |
| Carpathia PCI Limited | Administrative & support | 2014 |
| Carpentry & Building Masters Ltd | Manufacturing | 2017 |
| Carter Mcdonnell Consulting Ltd | Construction | 2023 |
| Carter's Electrical Solutions Ltd | Construction | 2019 |
| Casa Julia Limited | Wholesale & retail | 1975 |
| Case Pilots Connect Limited | Professional & scientific | 2022 |
| Casey Scaffold Consultants Ltd | Professional & scientific | 2025 |
| Cassiopeia Star Ltd | Administrative & support | 2024 |
| Castle Gent Builders Limited | Construction | 2012 |
| Castle Gent Holdings Limited | Real estate | 2022 |
| Castle Glass (Essex) Limited | Construction | 2019 |
| Castlekeep Limited | Transport & logistics | 1994 |
| Catering Management Consultants Limited | Professional & scientific | 2000 |
| Caulfield Civil Engineering Limited | Construction | 2014 |
| Caulfield Contractors Limited | Construction | 1983 |
| Cavalex Models Limited | Manufacturing | 2017 |
| CB Specialist Cars Ltd | Wholesale & retail | 2024 |
| CB the Bell Limited | Hospitality | 2023 |
| CBP Property Ltd | Real estate | 2020 |
| Cbrs Consulting Ltd | Information & communication | 2014 |
| CCM Education and Health Management Consultants Limited | Professional & scientific | 2011 |
| Ccs-Uk Ltd | Wholesale & retail | 2025 |
| Cdms Management UK Ltd | Administrative & support | 2014 |
| Celtic Rose (Construction) Limited | Real estate | 2021 |
| Celtic Rose (Property) Limited | Wholesale & retail | 2010 |
| Centaur Construction Ltd | Construction | 2017 |
| Centerline Publishing Group Ltd | Information & communication | 2024 |
| Central Cctv Limited | Administrative & support | 2016 |
| Central Fire & Safety Limited | Wholesale & retail | 2008 |
| Centre Point Roofing Services Ltd | Construction | 2016 |
| Ceramic and Marble Tiling Limited | Construction | 2014 |
| Cerf Limited | Information & communication | 2020 |
| Cesm Installations Limited | Construction | 2023 |
| Ceyket Fashion Ltd | Manufacturing | 2021 |
| Cfbc Limited | Information & communication | 2009 |
| CFF Management Ltd | Professional & scientific | 2014 |
| Chadwell Developments Limited | Construction | 2008 |
| Chalice Markets Ltd | Professional & scientific | 2018 |
| Chalk Holdings Limited | Real estate | 2019 |
| Challis Lane Ltd | Wholesale & retail | 2018 |
| Chambers Finance Solutions Ltd | Financial services | 2015 |
| Changing Destinies Ltd | Health & social care | 2018 |
| Chapel Hill Auto Services Ltd | Manufacturing | 2014 |
| Chapman Auto Engineering Limited | Wholesale & retail | 2016 |
| Charaka Wellness Ltd | Administrative & support | 2017 |
| Charlie Deakin-Davies Ltd | Information & communication | 2019 |
| Charlies House Childminding and Nursery Limited | Health & social care | 2023 |
| Charlotte's Angels Limited | Administrative & support | 2025 |
| Charloutay Ltd | Information & communication | 2026 |
| Chas. J. Townrow & Sons Limited | Wholesale & retail | 1963 |
| Check My Hearing Ltd | Health & social care | 2020 |
| Chelle’S Boutique Ltd | Wholesale & retail | 2019 |
| Chelmer Foods Limited | Manufacturing | 1992 |
| Chelmer Glass & Co Limited | Wholesale & retail | 2026 |
| Chelmer Hospitality Ltd | Hospitality | 2024 |
| Chelmer Mouldings Ltd | Manufacturing | 2013 |
| Chelmer Property Limited | Real estate | 2025 |
| Chelmer UK Holdings Limited | Real estate | 2021 |
| Chelmsford HIP and Knee Ltd | Health & social care | 2021 |
| Chelmsford Inhouse Vending Ltd | Wholesale & retail | 2022 |
| Cherry International Food Centre Ltd | Wholesale & retail | 2024 |
| Cherry Picked Flowers Ltd | Wholesale & retail | 2026 |
| Chestnut Properties (UK) Limited | Real estate | 2006 |
| Chiarli Ltd | Hospitality | 2017 |
| Chifra Ltd | Health & social care | 2024 |
| Chilford Court (Management) Limited | Households | 1988 |
| Chinite Resourcing Limited | Health & social care | 2009 |
| Chinnery Carpets Limited | Wholesale & retail | 2010 |
| Chiptech.Clothing Ltd | Wholesale & retail | 2025 |
| Chiptech.Design Ltd | Manufacturing | 2025 |
| Chiptech.Vision Ltd | Manufacturing | 2025 |
| Chiro Recruit Limited | Information & communication | 2013 |
| Chris COX Electrical Ltd | Construction | 2022 |
| Chris Lodge & Sons (Auto Repairs) Ltd | Wholesale & retail | 2011 |
| Chris Todd Interiors Limited | Other services | 2008 |
| Christa Davis Limited | Professional & scientific | 1998 |
| Christchurch Dwellings Limited | Real estate | 2020 |
| Christchurch Pharmacy Limited | Health & social care | 2008 |
| Christchurch Pre-School Nursery Limited | Health & social care | 2015 |
| Christie Electrical Services Ltd | Construction | 2016 |
| CHS Plumbing Ltd | Construction | 2023 |
| Chunky Charlies Limited | Hospitality | 2024 |
| Church END Farming Limited | Agriculture & fishing | 2018 |
| Church Park Management Limited | Households | 1984 |
| Churchfields Management Limited | Households | 1985 |
| CIL Systems Ltd | Manufacturing | 2022 |
| Circuit Hive Electrical Limited | Construction | 2026 |
| City and Guide Ltd | Real estate | 2022 |
| City Contracts Limited | Construction | 2024 |
| City Wastewater Drainage Limited | Water & waste | 2013 |
| CJ Aura Limited | Wholesale & retail | 2025 |
| Cjpr Limited | Real estate | 2025 |
| Claire Bottone Travel Ltd | Administrative & support | 2017 |
| Claire C Cullen Ltd | Professional & scientific | 2013 |
| Claire Y Smith Limited | Administrative & support | 2023 |
| Clarity Bauen Limited | Construction | 2025 |
| Clarity Financial Planning Limited | Financial services | 2020 |