| Chimneys R TED Ltd | Administrative & support | 2024 |
| Chris Brown (Downham Market) Limited | Wholesale & retail | 2005 |
| Christopher Clark Workshops Limited | Manufacturing | 1996 |
| Church Cottages (Nordelph) Management Company Limited | Administrative & support | 2014 |
| Cillacam Photography Limited | Information & communication | 2021 |
| Clay Hall Kennels Limited | Agriculture & fishing | 2020 |
| Clay Heating Services Ltd | Construction | 2026 |
| Clements and King Electrical Contractors Limited | Construction | 2018 |
| Clements and King Limited | Real estate | 2005 |
| Clifford Construction (Norfolk) Limited | Construction | 2004 |
| Clingbrook Limited | Manufacturing | 1979 |
| Clitheroe Agricultural Engineering Limited | Manufacturing | 2011 |
| Clover Community Care CIC | Health & social care | 2026 |
| Coach KYM Ltd | Administrative & support | 2022 |
| Coastal Locations Limited | Professional & scientific | 2023 |
| Coastal Path Leisure Ltd | Hospitality | 2026 |
| Coffee Speed Limited | Manufacturing | 2024 |
| Coldstores Limited | Construction | 2006 |
| Collaboratehq Ltd | Information & communication | 2008 |
| Complete Architecture Ltd | Construction | 2016 |
| Complete Plans Ltd | Construction | 2011 |
| Conrad Higgs Design Ltd | Professional & scientific | 2005 |
| Construction & Aerial Surveying LLP | | 2018 |
| Contemplation Corner Ltd | Construction | 2020 |
| Convalexa Consultancy Limited | Hospitality | 2024 |
| Convalexa Limited | Manufacturing | 2024 |
| Cootes Court (FEN Drayton) Management Company Limited | Hospitality | 2003 |
| Cordner Wealth Management Limited | Financial services | 2019 |
| County Vegetables Limited | Wholesale & retail | 2006 |
| Cowboy Competitions Ltd | Arts & recreation | 2025 |
| Craft Hair Line Ltd | Wholesale & retail | 2025 |
| Craft Hairdressers Ltd | Other services | 2022 |
| Crawford Financial Consulting Limited | Financial services | 2014 |
| CRC Collective Limited | Financial services | 2024 |
| CRC Electrical & Renewables Limited | Manufacturing | 2021 |
| CRC Letting Limited | Real estate | 2024 |
| CRC Scaffolding and Roofing Limited | Construction | 2025 |
| Crosson Consulting Limited | Professional & scientific | 2015 |
| Crow Hall Mews Management Company Limited | Administrative & support | 2004 |
| Crowfields Management Limited | Households | 2025 |
| Cruel Intention Tattoos Ltd | Other services | 2021 |
| Cruise Performers (Essex) Ltd | Arts & recreation | 2005 |
| CSB Rentals Holdings Ltd | Financial services | 2024 |
| Cymbaster Limited | Households | 1987 |
| D D (Outwell) Limited | Water & waste | 2015 |
| D.& H.Harrod(Coaches)Limited | Transport & logistics | 1965 |
| D.Coates Electrical Ltd | Construction | 2023 |
| Daler Viking Ltd | Information & communication | 2025 |
| DAM Hill Estates Ltd | Real estate | 2022 |
| DAM Hill Leisure Ltd | Hospitality | 2026 |
| Darvel Developments Ltd | Construction | 2004 |
| David Long Architecture Limited | Construction | 2005 |
| Dents Fisheries Limited | Agriculture & fishing | 2012 |
| Dents of Hilgay Limited | Wholesale & retail | 2011 |
| Denver Building & Landscaping Ltd | Construction | 2019 |
| Design Manage Construct Limited | Extraterritorial | 2011 |
| Develory Homes North Camb Ltd | Real estate | 2020 |
| Develory Homes South Camb Ltd | Real estate | 2021 |
| Develory Ltd | Construction | 2020 |
| DGA Cars Limited | Wholesale & retail | 2014 |
| Dghs Projects Ltd | Construction | 2025 |
| Digglenet Limited | Information & communication | 2000 |
| Digital Change Services Ltd | Information & communication | 2025 |
| Digital House Limited | Information & communication | 2001 |
| DNM (UK) Ltd | Professional & scientific | 2004 |
| Dolce Amore Ltd | Hospitality | 2025 |
| Dorplan LLP | | 2007 |
| Downham Autocare Limited | Wholesale & retail | 2014 |
| Downham Cider Company Limited | Extraterritorial | 2004 |
| Downham Cutz Limited | Other services | 2025 |
| Downham Fitness Ltd | Other services | 2023 |
| Downham Gents Ltd | Other services | 2024 |
| Downham Ladies Fitness (DM) Ltd | Other services | 2023 |
| Downham Market Christmas Lights Limited | Public administration | 2016 |
| Downham Market Management Limited | Professional & scientific | 2013 |
| Downham Market Nails Bar Ltd | Other services | 2026 |
| Downham Nursery School Limited | Education | 2023 |
| Downham Property Solutions Ltd | Real estate | 2023 |
| Downham Sparkit Ltd | Construction | 2024 |
| Downham Town Social Club Limited | Arts & recreation | 2023 |
| DPS (Norfolk) Limited | Construction | 2014 |
| Dōngxi Ltd | Hospitality | 2025 |
| E F Motor Services Ltd | Wholesale & retail | 2024 |
| E.W.Kisby and Sons Limited | Agriculture & fishing | 1958 |
| E10 Competitions Ltd | Wholesale & retail | 2025 |
| Eagles Coaches Limited | Transport & logistics | 2010 |
| Eagles Holdings (EA) Limited | Financial services | 2024 |
| Eagles Project Management Limited | Professional & scientific | 2020 |
| Earth Magick Limited | Wholesale & retail | 2026 |
| Earthgroup Limited | Extraterritorial | 2002 |
| East Anglia Renewables Centres Limited | Wholesale & retail | 2021 |
| East Anglia Staycation Services Ltd | Administrative & support | 2021 |
| East Anglian Storage Limited | Real estate | 2009 |
| East Coast Signs Property Limited | Real estate | 2015 |
| East County Classics Limited | Wholesale & retail | 2017 |
| East Hall Management Company Limited | Real estate | 2004 |
| Eastern Counties Knotweed Ltd | Agriculture & fishing | 2016 |
| Easy Splice Ltd | Wholesale & retail | 2021 |
| EB Cars Ltd | Wholesale & retail | 2026 |
| Ecoutai Limited | Information & communication | 2021 |