| Civils & Networks Limited | Construction | 2018 |
| CJ International Services Limited | Administrative & support | 2017 |
| CJN Civils & Groundworks Ltd | Construction | 2022 |
| Classic and Retro Warehouse Limited | Transport & logistics | 2021 |
| Classic Car Imports (Norfolk) Limited | Wholesale & retail | 2012 |
| Classic Hangar Ltd | Wholesale & retail | 2023 |
| Classic Offroad Ltd | Wholesale & retail | 2019 |
| Classypaws Limited | Financial services | 2008 |
| Clavarez Estates Ltd | Real estate | 2026 |
| Clearacre Farming Limited | Agriculture & fishing | 1997 |
| CLG Norfolk Limited | Agriculture & fishing | 2010 |
| CLN Property Management Ltd | Real estate | 2026 |
| Clopick Limited | Professional & scientific | 2012 |
| CMG Agronomy Limited | Agriculture & fishing | 2018 |
| CMG Property Rental Limited | Households | 2022 |
| Coach House Estimating Limited | Professional & scientific | 2020 |
| Coco Aviation Services Ltd | Manufacturing | 2026 |
| Code 13 Limited | | 1991 |
| Codebots Ltd | Administrative & support | 2016 |
| Coldclicks Limited | Information & communication | 2024 |
| Colw | Other services | 2012 |
| Comfort Taxi Limited | Transport & logistics | 2025 |
| Commodity Research Management Global Limited | Wholesale & retail | 2013 |
| Community Action Norfolk | Public administration | 1996 |
| Comprotec UK Ltd | Professional & scientific | 2006 |
| Computational Immunology Research and Development Ltd | Professional & scientific | 2018 |
| Connor Cooper Carbon Limited | Manufacturing | 2024 |
| Conserve Energy Ltd | Manufacturing | 2011 |
| Contiro Limited | Administrative & support | 2006 |
| Convertly Ltd | Information & communication | 2024 |
| Cooperwaite Security Ltd | Administrative & support | 2019 |
| Copper Reef Limited | Wholesale & retail | 2022 |
| Coppersmith Holdings Limited | Financial services | 2024 |
| Core Recruiter Ltd | Administrative & support | 2016 |
| Corriedale Ltd | Professional & scientific | 2016 |
| Corroless Eastern Limited | Manufacturing | 2001 |
| Cottage Concierge Services Limited | Other services | 2017 |
| Cotton World by STB Apparel Limited | Wholesale & retail | 2025 |
| Countryside Storage Solutions Ltd | Real estate | 2017 |
| County School Residents Association Limited | Households | 2002 |
| Cover Corp Ltd | Wholesale & retail | 2019 |
| Cowper Road Properties Limited | Real estate | 1964 |
| CQ Cleaning Limited | Other services | 2016 |
| Crafted Oak Ltd | Manufacturing | 2021 |
| Crafty Flair Limited | Wholesale & retail | 2020 |
| CRC Consultancy Limited | Professional & scientific | 2021 |
| Creating Shade Ltd | Construction | 2021 |
| Crestcalm Ltd | Wholesale & retail | 2025 |
| Crista-Popovici Ltd | Health & social care | 2019 |
| Cromwell Mews Management Limited | Households | 1987 |
| Cruinn Property Ltd | Real estate | 2026 |
| Cryo Automotive Ltd | Administrative & support | 2025 |
| CS Spectrum Ltd | Professional & scientific | 2026 |
| CT Plant Training Services Ltd | Education | 2019 |
| Curly YOU Cosmetics Limited | Wholesale & retail | 2022 |
| Curry Muncherz Limited | Hospitality | 2026 |
| Custom Residential Ltd | Real estate | 2019 |
| Cutting Automotive Ltd | Wholesale & retail | 2018 |
| D & M Brownlee Limited | Wholesale & retail | 2006 |
| D J Thompson Limited | Construction | 2004 |
| D R Brown Contracts Ltd | Water & waste | 2022 |
| D T J Developments Ltd | Construction | 2022 |
| D T P Golf Sales Limited | Wholesale & retail | 2012 |
| D&A Auto Thetford Ltd | Wholesale & retail | 2017 |
| D&B Property Holdings Limited | Real estate | 2021 |
| D. Thurlow Limited | Agriculture & fishing | 2018 |
| D.A.P. Building and Construction Services Limited | Construction | 2002 |
| D.M. Video Services Limited | Information & communication | 2000 |
| Dale Brown Construction Services Ltd | Construction | 2018 |
| Daley Recruitment Ltd | Administrative & support | 2021 |
| Daltaic Ltd | Energy | 2025 |
| Danino Consulting Ltd | Professional & scientific | 2023 |
| Darkforge Labs Ltd | Information & communication | 2026 |
| Darkhaze Limited | Wholesale & retail | 2020 |
| Dart Technical Services Ltd | Professional & scientific | 2010 |
| Datatrace Data Recovery Services Limited | Extraterritorial | 2012 |
| David a. Cutting Building Surveyors Limited | Professional & scientific | 1983 |
| David Carbutt Limited | Construction | 2017 |
| David Holliday Limited | Manufacturing | 2007 |
| David James Tracey Ltd | Construction | 2023 |
| David Relph Ltd | Manufacturing | 2016 |
| Davison Carpentry Ltd | Construction | 2024 |
| DC Personnel Limited | Administrative & support | 2020 |
| Dc's Bar Ltd | Hospitality | 2017 |
| DCT Recruitment Ltd | Administrative & support | 2021 |
| Dead Men's Spex Limited | Other services | 2015 |
| Dean Garnham Transport Service Ltd | Transport & logistics | 2013 |
| Dean Moulton Building Services Ltd | Construction | 2011 |
| Defined by Izzy Ltd | Other services | 2024 |
| Den-Teq Ltd | Health & social care | 2025 |
| DER Solutions Limited | Other services | 2022 |
| Dereham Accommodation Agency Ltd | Real estate | 2014 |
| Dereham APO Ltd | Hospitality | 2025 |
| Dereham Blues Festival | Arts & recreation | 2015 |
| Dereham Day Limited | Arts & recreation | 2024 |
| Dereham Decorating Supplies Ltd | Wholesale & retail | 2019 |
| Dereham Dog DEN Ltd | Other services | 2024 |
| Dereham Domestic Appliances Limited | Other services | 2014 |
| Dereham Glass Limited | Construction | 2003 |
| Dereham Medical Services Limited | Wholesale & retail | 2023 |