| C & H Hospitality Ltd | Professional & scientific | 2024 |
| C D C Blowers Limited | Agriculture & fishing | 2009 |
| C J Gordon Limited | Professional & scientific | 2010 |
| C.E. Ruth Ltd | Construction | 2005 |
| C.S. Buchanan Holdings Limited | Financial services | 2018 |
| C.S. Buchanan Limited | Real estate | 1988 |
| C.W. & J Cargill Holdings Limited | Financial services | 2024 |
| C.W. & J. Cargill Limited | Agriculture & fishing | 1960 |
| Cakes by Tasha Limited | Wholesale & retail | 2026 |
| Callena Limited | Professional & scientific | 2013 |
| Calmont King & Co.,Limited | Construction | 1908 |
| Calthorpe House Limited | Households | 1994 |
| Care and Quality Ltd | Health & social care | 2017 |
| Care VS Ltd | Health & social care | 2019 |
| Carinae Ltd | Professional & scientific | 2019 |
| Cessatio Ltd | Hospitality | 2023 |
| CGL Design Limited | Construction | 2011 |
| Chapel Road Accounting Services Limited | Professional & scientific | 2003 |
| Charles Long Limited | Agriculture & fishing | 1961 |
| Cherry Tree Farm Management Company Limited | Households | 2008 |
| Cheyney Green Management Co Ltd | Households | 2019 |
| Chiaroscuro Curation Limited | Wholesale & retail | 2023 |
| Chloe Kinrade School of Dance Ltd | Education | 2025 |
| Chloe Stewart Consulting Limited | Professional & scientific | 2025 |
| Choose Better Ltd | Information & communication | 2016 |
| Chopping's Hill Limited | Wholesale & retail | 2022 |
| Chris's Tree Services Ltd | Agriculture & fishing | 2019 |
| Christies Care Farms Ltd | Agriculture & fishing | 2025 |
| Christies Care Ltd | Other services | 1991 |
| Civilsvsa Ltd | Construction | 2023 |
| Claire Gawthrop Counselling Ltd | Administrative & support | 2020 |
| Clark With NO E Limited | Wholesale & retail | 2023 |
| Clean Tabs Limited | Other services | 1988 |
| Clive Welton & Partners Limited | Construction | 2007 |
| Cloche Property Limited | Real estate | 2019 |
| Coastal Cleaning Crew Ltd | Administrative & support | 2021 |
| Coldfair Butchers Arms Ltd | Hospitality | 2024 |
| Comzo Ltd | Real estate | 2025 |
| Conisby Consulting Ltd | Professional & scientific | 2021 |
| Connected East Ltd | Professional & scientific | 2025 |
| Connie and Co Limited | Information & communication | 2008 |
| Copacetic Services Limited | Professional & scientific | 2026 |
| Copperbeech BED and Breakfast Ltd | Hospitality | 2026 |
| Cotton Tree Interiors Limited | Wholesale & retail | 2012 |
| Countywide Domestic Services Ltd. | Households | 2007 |
| Coxage Property Ltd | Real estate | 2017 |
| Cranfield Farm Ltd | Agriculture & fishing | 2025 |
| Crick Ventures Limited | Real estate | 2024 |
| Crisp 'N' Clean Ltd | Administrative & support | 2022 |
| Cross Surveys Ltd | Professional & scientific | 2013 |
| Crossmore Trading Limited | Professional & scientific | 2016 |
| CT Interiors Holdings Limited | Financial services | 2021 |
| CTI Enterprises Limited | Wholesale & retail | 2012 |
| Ctka Limited | Administrative & support | 2021 |
| Cuillean Mccausland Ltd | Construction | 2018 |
| Cult Classic Restorations Ltd | Wholesale & retail | 2017 |
| Culture Edit Suffolk C.I.C. | Information & communication | 2026 |
| Cursed Survival Island Limited | Other services | 2025 |
| D & M Driver (Suffolk) Ltd | Construction | 2017 |
| D J Sugrue Ltd | Construction | 2019 |
| D. Freeman Services Limited | Manufacturing | 2012 |
| DAC Education Ltd | Education | 2020 |
| Darsham Country Centre | Hospitality | 1993 |
| Darsham Old Hall Limited | Agriculture & fishing | 2023 |
| David Cargill (Farms) Limited | Agriculture & fishing | 1997 |
| DBS Technical Solutions Limited | Information & communication | 2010 |
| Deacon Solutions Limited | Real estate | 2025 |
| Debs the Dog Walker Ltd | Other services | 2025 |
| Denhall Farming Limited | Real estate | 2024 |
| Dhotel Patisserie Limited | Hospitality | 2012 |
| Dhotel's Home Ltd | Hospitality | 2024 |
| Dimwittie Films Limited | Information & communication | 2013 |
| Dingle Hill Tearooms Limited | Hospitality | 2014 |
| Disco Volante 24 Ltd | Wholesale & retail | 2024 |
| Dlek Electrical Ltd | Construction | 2020 |
| Dogs Yard Ltd | Extraterritorial | 2025 |
| Dogsbody Group Ltd | Other services | 2021 |
| Donovan Lightweight Cycles Ltd | Wholesale & retail | 2021 |
| DP Theatrical Limited | Administrative & support | 2015 |
| Drayson Law Limited | Administrative & support | 2007 |
| DRC Auto Sales Ltd | Wholesale & retail | 2024 |
| Drivewise Global Limited | Information & communication | 2025 |
| Druce Ventures Ltd | Real estate | 2023 |
| Drywood Ltd | Agriculture & fishing | 2003 |
| DS Memorials Ltd | Manufacturing | 2025 |
| Dtaylorlandscapes Limited | Administrative & support | 2016 |
| DTM Power Limited | Wholesale & retail | 2004 |
| Duggan Building Services Ltd | Construction | 2017 |
| Dunwich Equestrian Limited | Agriculture & fishing | 2025 |
| Dunwich Greyfriars Trust | Arts & recreation | 2012 |
| DVC Enterprises Ltd | Information & communication | 2020 |
| Dyslexia School Search Limited | Education | 2015 |
| E & J Fire Systems Ltd | Manufacturing | 2013 |
| Early Music Holdings Limited | Information & communication | 2018 |
| Early Music Shop Limited | Wholesale & retail | 2007 |
| East Green Power 11 Limited | Manufacturing | 2020 |
| East Suffolk Donkey Sanctuary CIC | Agriculture & fishing | 2022 |
| Eastern Seed Services Ltd | Agriculture & fishing | 2016 |
| Eastorage Limited | Transport & logistics | 2022 |
| Edmondson Group Limited | Administrative & support | 2022 |