| Create Succeed Ltd | Professional & scientific | 2024 |
| Crem Recruitment Limited | Administrative & support | 2007 |
| Crest Stud Limited | Agriculture & fishing | 1987 |
| Crevox Ltd | Information & communication | 2025 |
| CRF Racing Services Ltd | Agriculture & fishing | 2020 |
| Crimsonfox Limited | Professional & scientific | 2023 |
| Cristian Mirzan Ltd | Transport & logistics | 2022 |
| CRJ Carpentry and Construction Limited | Construction | 2025 |
| CRJ Carpentry Limited | Manufacturing | 2022 |
| Croftbench Limited | Extraterritorial | 1975 |
| Cromwell Business Systems Limited | Information & communication | 2003 |
| Cromwell IP Limited | Real estate | 2020 |
| Crosby Ventures Limited | Professional & scientific | 2019 |
| Crownhill Associates Limited | Information & communication | 1994 |
| Crownmotorsales Ltd | Wholesale & retail | 2026 |
| Crudu Group Ltd | Construction | 2016 |
| Crystal Diamonds Ltd | Administrative & support | 2016 |
| CSL Newmarket Electrical Ltd | Construction | 2024 |
| CSM Media Ltd | Wholesale & retail | 2020 |
| CSR Performance Limited | Information & communication | 2007 |
| CT Construction Group Ltd | Construction | 2023 |
| Cubic Flow Ltd | Extraterritorial | 2025 |
| Cubiq Properties Limited | Wholesale & retail | 2020 |
| Cubiqdesign Limited | Arts & recreation | 2008 |
| Curve Recruitment Solutions Ltd | Administrative & support | 2024 |
| Czech Estates Investments Ltd | Real estate | 2017 |
| D a Landscaping & Garden Services Limited | Administrative & support | 2021 |
| D B Business Services Limited | Professional & scientific | 2015 |
| D C R Contracts Limited | Construction | 2007 |
| D Collis Consulting Limited | Administrative & support | 2011 |
| D M Hills Limited | Manufacturing | 2003 |
| D M Tree & Landscape Contractors Limited | Administrative & support | 2015 |
| D O R Property Developments Ltd | Real estate | 1998 |
| D W Tonge Electrical Ltd | Construction | 2017 |
| D&G Market Ltd | Wholesale & retail | 2026 |
| D&S Electrical Installations Ltd | Construction | 2021 |
| D&S Properties (Suffolk) Ltd | Real estate | 2024 |
| D. Haird & Company Limited | Water & waste | 1974 |
| D.Donald.Flat.Roofing Ltd | Construction | 2024 |
| D.T. Brown & Company Limited | Manufacturing | 1994 |
| DA Ltd | Extraterritorial | 2009 |
| Daban Bloodstock Limited | Agriculture & fishing | 2023 |
| Daisy Hill Feeds Limited | Extraterritorial | 1970 |
| Dale Burch and SON Ltd | Construction | 2011 |
| Dale Jeffery Electrical Services Limited | Construction | 2000 |
| Dalham Developments Limited | Construction | 2023 |
| Dalham Estates Limited | Agriculture & fishing | 1976 |
| Dalham Investments Limited | Agriculture & fishing | 2005 |
| Damian's Transport Services Ltd | Transport & logistics | 2024 |
| DAN Sumner Limited | Real estate | 2021 |
| Daniel Geach Ltd | Financial services | 2019 |
| Daniel Schumann Limited | Arts & recreation | 2009 |
| Dar-T Services Limited | Transport & logistics | 2008 |
| Darlac Limited | Manufacturing | 2003 |
| Darley Stud Management Company Limited | Extraterritorial | 1984 |
| David Lockhart Limited | Education | 2024 |
| David Simcock Racing Ltd | Arts & recreation | 2003 |
| Davis Recruitment Services Limited | Administrative & support | 2025 |
| Davison Farms (Suffolk) Limited | Administrative & support | 1996 |
| Day Computer Corporation Limited | Information & communication | 2000 |
| Day Group (UK) Limited | Information & communication | 1999 |
| Day Telecommunications Limited | Information & communication | 2006 |
| DB Equine Limited | Agriculture & fishing | 2026 |
| DC Property (Cambs) Limited | Real estate | 2026 |
| DCB Consultancy Services Limited | Professional & scientific | 2021 |
| DCM Pro Haulage Ltd | Transport & logistics | 2026 |
| DE Sangosse Ltd. | Wholesale & retail | 1993 |
| DE2SUN Properties Ltd | Real estate | 2023 |
| Dealt PLC | Transport & logistics | 1998 |
| Dear Love Limited | Manufacturing | 2017 |
| Debarkle Property Holdings Limited | Real estate | 2019 |
| Deborah Hargreaves Limited | Professional & scientific | 2012 |
| December Ltd | Extraterritorial | 2022 |
| Deepdive Medchem Consulting Ltd | Professional & scientific | 2024 |
| Delicious Mountain SKI Chalets Limited | Administrative & support | 2020 |
| Delish Pizza Ltd | Hospitality | 2020 |
| DEN TAN Limited | Health & social care | 2024 |
| Denson Domestic Cleaning Services Limited | Administrative & support | 2014 |
| Deputla Ltd | Health & social care | 2021 |
| Derby Cottage Clinic Limited | Health & social care | 2006 |
| Derby Cottage Wellness Ltd | Health & social care | 2025 |
| Design Management Architecture Ltd | Information & communication | 2015 |
| Devon Hideaways Limited | Extraterritorial | 2021 |
| DG Write & Review Limited | Information & communication | 2016 |
| DGF Surfacing Ltd | Construction | 2025 |
| DI Ltd | Extraterritorial | 2009 |
| Diasma Limited | Real estate | 1993 |
| Diasma Property Services Limited | Administrative & support | 2009 |
| Dick White Referrals Limited | Professional & scientific | 2005 |
| Didi & Jooles Ltd | Manufacturing | 2021 |
| Digital Imagination Industries Limited | Information & communication | 2025 |
| Discover Newmarket Community Interest Company | Administrative & support | 2014 |
| Discovery Biology Ltd | Professional & scientific | 2025 |
| Discovery Legal Recruitment Limited | Administrative & support | 2022 |
| Dislodge Designs Ltd | Professional & scientific | 2025 |
| Display Champ Ltd | Manufacturing | 2024 |
| Distant Lands Ltd | Wholesale & retail | 2018 |
| Diver Ltd | Professional & scientific | 2016 |
| Divorce, Mediation & Family Law Limited | Professional & scientific | 2013 |
| DLF Holdings Limited | Other services | 2022 |