| Copperbottom Properties Limited | Real estate | 1999 |
| Corin Builders Limited | Construction | 1988 |
| Cornelius Specialties Ltd | Manufacturing | 2006 |
| Corpowise Limited | Wholesale & retail | 2022 |
| Corton Estates Limited | Real estate | 2000 |
| Countrylife Stoves Limited | Construction | 1985 |
| Countywide Properties Limited | Real estate | 1999 |
| Coytes Gardens Management Co. Limited | Households | 2004 |
| CPC Technologies UK Limited | Professional & scientific | 2004 |
| CPS Builders (Developments) Ltd | Construction | 2005 |
| CRC Consultant Ltd | Professional & scientific | 2019 |
| Creative Audio Ltd | Extraterritorial | 2020 |
| Creative Couture Salon Limited | Other services | 2005 |
| Creature Sound Limited | Information & communication | 2017 |
| Crescita Advisory Ltd | Professional & scientific | 2023 |
| Cresign Ltd | Professional & scientific | 2006 |
| Crestflareart Ltd | Wholesale & retail | 2025 |
| Crockfords Flats (NO 1) Management Company Ltd | Households | 1980 |
| Crofton New Homes and Developments Limited | Wholesale & retail | 1984 |
| Cromlech Bloodstock Limited | Professional & scientific | 2024 |
| CRW Limited | Extraterritorial | 1993 |
| CRX Developments Limited | Construction | 2025 |
| Cubitt Theobald Limited | Construction | 1944 |
| Culford School (Trading Trust) Limited | Arts & recreation | 1979 |
| Culford Waste Limited | Water & waste | 2003 |
| Culwell House Management Company Limited | Real estate | 1977 |
| Cupido Recruitments Ltd | Administrative & support | 2020 |
| CUSTOMI3D Ltd | Wholesale & retail | 2024 |
| CVR Holdings Ltd | Financial services | 2025 |
| Cyberocean Limited | Other services | 2010 |
| D a Spink Haulage Limited | Transport & logistics | 2003 |
| D C Patrick Newsagents | | 2003 |
| D J Howlett Motor Engineers Ltd | Wholesale & retail | 2002 |
| D J Sears Limited | Construction | 2007 |
| D R Driveways Limited | Construction | 2018 |
| D&J Studio Ltd | Manufacturing | 2020 |
| D'Divas Beauty Care Limited | Wholesale & retail | 2025 |
| D. L. Fuller Limited | Construction | 2006 |
| D.B. Sheetmetals Limited | Manufacturing | 1988 |
| D.Gurteen & Sons,Limited | Manufacturing | 1929 |
| D.J. Evans (Bury) Limited | Wholesale & retail | 1957 |
| D4TL Studios Ltd | Wholesale & retail | 2022 |
| Dance Vibe Limited | Wholesale & retail | 2005 |
| Dandy Dogs Limited | Other services | 2002 |
| Daniel Piper Motor Services Limited | Wholesale & retail | 2007 |
| Danisco (UK) Limited | Manufacturing | 1988 |
| Dash Delivery Limited | Information & communication | 2022 |
| Data Lucidity Ltd | Information & communication | 2023 |
| Data Shaman Ltd | Information & communication | 2024 |
| Dataflow (International) Limited | Information & communication | 2000 |
| Dataflow (U.K.) Limited | Information & communication | 1981 |
| Datarapt Limited | Information & communication | 2007 |
| Davan Hygienics UK Ltd | Manufacturing | 2023 |
| David Walters Fabrics Limited | Extraterritorial | 1986 |
| David Whittle & Co Limited | Professional & scientific | 2003 |
| Davin Place Limited | Wholesale & retail | 2025 |
| Dawng Tech Ltd | Wholesale & retail | 2026 |
| Dawsan Limited | | 1986 |
| Day Trading Rauf Ltd | Other services | 2023 |
| DCH Builders Limited | Construction | 2002 |
| Deannaguenther Ltd | Wholesale & retail | 2025 |
| Deben Network Solutions Ltd | Information & communication | 2002 |
| Deben Plumbing and Heating Limited | Construction | 2003 |
| Dedoyin Ltd | Health & social care | 2022 |
| Deegbades Ltd | Wholesale & retail | 2024 |
| Deep Data Ltd | Information & communication | 2018 |
| Defendra Ltd | Information & communication | 2024 |
| Deja-Vu Sandwich Bar Cafe Limited | Hospitality | 2003 |
| Dellview Limited | Real estate | 2006 |
| Delos & Lester Ltd | Real estate | 2023 |
| Denny Bros Holdings Limited | Real estate | 1995 |
| Denny Bros Limited | Manufacturing | 1983 |
| Denny Bros Trustee Limited | Financial services | 2021 |
| Denny of Southwold Limited | Wholesale & retail | 1958 |
| Developing Younger Minds Limited | Professional & scientific | 2007 |
| DIA Yacht Limited | Professional & scientific | 2024 |
| Dialogic Consulting Limited | Professional & scientific | 2006 |
| Diamond Management Consultancy Ltd | Professional & scientific | 2011 |
| Dibcan Limited | Health & social care | 1989 |
| Digidreamer UK Ltd | Wholesale & retail | 2023 |
| Digitaevolve Ltd | Information & communication | 2023 |
| Digital Lolly Ltd | Professional & scientific | 2021 |
| Dimensional Wave Ltd | Information & communication | 2012 |
| Dipjyot UK Limited | Wholesale & retail | 2017 |
| Disciplinae Advisory Limited | Professional & scientific | 2024 |
| DL Design Associates Limited | Professional & scientific | 2006 |
| DL Homes & Rentals Ltd | Real estate | 2025 |
| DMS Total Solutions Limited | Administrative & support | 2022 |
| Dolvers View (Holywell ROW) Management Company Limited | Households | 2006 |
| DON Fraser Print | | 1994 |
| Donna Crain Limited | Manufacturing | 2012 |
| Door Services Plus Limited | Administrative & support | 2002 |
| Dopson Builders Limited | | 1976 |
| Dorothy MAY Holdings Limited | Construction | 1989 |
| Dorrett Limited | Health & social care | 2015 |
| Dove Court (Saxmundham) Management Company Limited | Households | 1992 |
| Doyle Electrical Services Limited | Construction | 1999 |
| DPD Properties Ltd | Real estate | 2021 |
| DPS & Sons Property Ltd | Real estate | 2022 |
| Draftfix Limited | Wholesale & retail | 2008 |