| Colin Clack Removers & Packers Limited | Transport & logistics | 2000 |
| Comfort Transfer London (CTP) Ltd | Transport & logistics | 2021 |
| Compassionate Care 4 U Limited | Public administration | 2025 |
| Complete Flooring Diss Ltd | Construction | 2024 |
| Complete Treecare & Landscapes Ltd | Administrative & support | 2026 |
| Concorde Publishing Limited | Information & communication | 2010 |
| Confiance Services Ltd | Professional & scientific | 2015 |
| Confucius International School Chengdu UK Branch Limited | Education | 2016 |
| Conkers Group Ltd | Education | 2022 |
| Conkers Holiday Lets Ltd | Hospitality | 2026 |
| Connected Facilities Management Limited | Transport & logistics | 2026 |
| Cooks Building Services Limited | Construction | 2007 |
| Cool Dimension Ltd | Transport & logistics | 2022 |
| Cooper & Daughters Ltd | Real estate | 2022 |
| Cooper Projects Limited | Financial services | 2016 |
| Cornish Garden Services Ltd | Administrative & support | 2025 |
| Corporate Growth Consultancy Limited | Professional & scientific | 2011 |
| Countermeasure Systems Limited | Public administration | 2014 |
| Country Homes (Bury Road Wortham) Residents Company Limited | Households | 2007 |
| Country Homes Developments (Redgrave) Management Company Limited | Real estate | 2004 |
| Countryside Services Heating Ltd | Construction | 2022 |
| Cousins Coffee Cart Ltd | Manufacturing | 2024 |
| Cowhams Enterprises Ltd | Construction | 2000 |
| COX T SOT Limited | Wholesale & retail | 2000 |
| CPI Developments Limited | Extraterritorial | 2015 |
| Craggman Limited | Professional & scientific | 2023 |
| Crane & Cernota Developments Ltd | Real estate | 2021 |
| Crawford Solutions Limited | Information & communication | 2002 |
| Creating Space Therapies Limited | Health & social care | 2016 |
| Creative Warehouse Ltd | Professional & scientific | 2018 |
| Croshaw Communications Ltd | Professional & scientific | 2019 |
| Crouch (Dehydrators) Limited | Agriculture & fishing | 1948 |
| Crucial Power (UK) Ltd. | Administrative & support | 2009 |
| Crystal Car Wash and Service Ltd | Wholesale & retail | 2023 |
| CTS DIY & Building Supplies Ltd | Wholesale & retail | 2020 |
| Cullum Agri Limited | Agriculture & fishing | 2024 |
| Cunningham Builders Limited | Construction | 2004 |
| Curated Hair Ltd | Other services | 2012 |
| Current Solutions Ltd | Extraterritorial | 2015 |
| Cuthbert Maltings Management (Diss) Limited | Construction | 2007 |
| CVS (UK) Limited | Professional & scientific | 1999 |
| CVS Group PLC | Professional & scientific | 2007 |
| Cycleaware Limited | Manufacturing | 2025 |
| Cyprium Ltd | Manufacturing | 2002 |
| D & C Plummer Limited | Construction | 2007 |
| D & M Wharton Limited | Agriculture & fishing | 2003 |
| D and T Tree Services Ltd | Agriculture & fishing | 2019 |
| D J Richardson Limited | Real estate | 2003 |
| D W Irving Ltd | Mining & quarrying | 2013 |
| D Warley Ltd | Manufacturing | 2019 |
| D. I. B. C. Ltd | Construction | 2019 |
| D.C Last Vehicle Sales Limited | Wholesale & retail | 2000 |
| D.K. Young & Associates Limited | Extraterritorial | 1999 |
| Dade Enterprises Limited | Real estate | 2024 |
| Daisywheel Interactive Ltd | Administrative & support | 2012 |
| Dallas & Martin Accountancy Ltd | Professional & scientific | 2010 |
| Danarbor Limited | Agriculture & fishing | 2008 |
| Dando Brickwork Ltd | Construction | 2025 |
| Darboe and Baily Limited | Professional & scientific | 2010 |
| Darrow Farm Fishery Ltd | Agriculture & fishing | 2016 |
| Darts Planet TV Group Limited | Information & communication | 2020 |
| Darts Reviews TV Limited | Extraterritorial | 2020 |
| Datamated Limited | Information & communication | 2011 |
| Davey Engineering Limited | Extraterritorial | 1998 |
| Davey-Walker Properties Ltd. | Extraterritorial | 1990 |
| David Brown Tractor Club (Suffolk & Norfolk) Limited | Other services | 2015 |
| David G Taylor Ltd | Real estate | 2025 |
| Deards Build Maintain Restore Ltd | Construction | 2025 |
| Deben Group Limited | Real estate | 2019 |
| DEF Healthcare Ltd | Health & social care | 2012 |
| Delivery Consulting Ltd | Professional & scientific | 2006 |
| Deltamoore Limited | Administrative & support | 1999 |
| Deltamoore Properties Ltd | Real estate | 2020 |
| Deltic Performance Engineering Limited | Real estate | 1996 |
| Deluxe Houses Ltd | Real estate | 2021 |
| Dermal Elegance Skin Care Clinic Ltd | Health & social care | 2012 |
| Design Bodega Limited | Professional & scientific | 2017 |
| Desira Group PLC | Wholesale & retail | 1990 |
| Dfas 20 Ltd | Professional & scientific | 2014 |
| DFC Precision Engineering Ltd | Manufacturing | 2011 |
| Dialoz Service Limited | Wholesale & retail | 2023 |
| Digital Amigo Limited | Information & communication | 2015 |
| Digital Taxidermy Ltd | Professional & scientific | 2020 |
| Direct Cable Systems Limited | Manufacturing | 1997 |
| Dirtbag IS Dead Limited | Wholesale & retail | 2023 |
| Diss & District Bowls Club Limited | Arts & recreation | 2016 |
| Diss Angling Centre Limited | Wholesale & retail | 2016 |
| Diss Business Centre Limited | Real estate | 2025 |
| Diss Business Park Properties Limited | Construction | 2018 |
| Diss Car Wash Ltd | Wholesale & retail | 2016 |
| Diss Chiropractic Clinic Limited | Health & social care | 2012 |
| Diss Christian Community Church | Other services | 2009 |
| Diss Community Partnership CIC CIC | Other services | 2002 |
| Diss Deli & Coffee Shop Ltd | Hospitality | 2023 |
| Diss Dental Health Centre Limited | Health & social care | 2009 |
| Diss Discount Ltd | Wholesale & retail | 2011 |
| Diss Electrical Solutions Ltd | Construction | 2016 |
| Diss Golf Club Limited | Arts & recreation | 2023 |
| Diss Golf Trading Limited | Hospitality | 2017 |
| Diss Hand Car Wash Ltd | Administrative & support | 2017 |