| Cryac Projects Limited | Construction | 2017 |
| Crystal Amusements Limited | Wholesale & retail | 2004 |
| Crystal Caviar Properties Limited | Real estate | 2018 |
| Crystal Corporate Catering Limited | Other services | 2019 |
| Crystal Grand Limited | Hospitality | 2023 |
| Crystal Oak Constructions Ltd | Construction | 2011 |
| CSE Investments Ltd | Households | 2018 |
| CSR Academy Limited | Education | 2019 |
| CT and Co Commercial Finance Limited | Financial services | 2026 |
| Ctrlt Solutions Ltd | Information & communication | 2018 |
| Cuboid Ltd. | Education | 2014 |
| Cuckoo Hill Consulting Limited | Professional & scientific | 2020 |
| Cuckoo Interim Limited | Professional & scientific | 2010 |
| Cultural Intelligence Hub Limited | Professional & scientific | 2015 |
| Cumberland Management Services Limited | Professional & scientific | 2025 |
| Cumbria Ventures Limited | Health & social care | 2022 |
| Cupidos Solutions Limited | Information & communication | 2013 |
| Curandera Ltd | Health & social care | 2020 |
| Curious Clothing Limited | Wholesale & retail | 2024 |
| Curlew Investment Ltd | Real estate | 2018 |
| Curry Masterclass Limited | Education | 2010 |
| Curve Auto Ltd | Wholesale & retail | 2022 |
| Curzon One Limited | Professional & scientific | 2017 |
| Custom Design Timber Windows Ltd | Construction | 2025 |
| Cutler & Goddard Limited | Professional & scientific | 2019 |
| CWG Services Limited | Administrative & support | 2005 |
| CY Real Estate Ltd | Real estate | 2025 |
| Cybernev Limited | Administrative & support | 2018 |
| Cybersmart Tutoring Limited | Education | 2025 |
| Cygnet House Residents Limited | Households | 1975 |
| CYM Consultants Ltd | Information & communication | 2025 |
| Cynosure Global Ltd | Information & communication | 2020 |
| Cyurable Ltd | Wholesale & retail | 2025 |
| D & E Consulting Limited | Education | 2018 |
| D & G Travel of Marlow Limited | Administrative & support | 2015 |
| D & H Consultants Ltd | Professional & scientific | 2021 |
| D & M (Park Royal) Ltd | Administrative & support | 2011 |
| D Amey Commercial Ltd | Administrative & support | 2025 |
| D Coffey Carpentry Ltd | Manufacturing | 2025 |
| D I Enterprises Limited | Transport & logistics | 2013 |
| D J Burling Limited | Professional & scientific | 2024 |
| D K K Consultancy Ltd | Information & communication | 1996 |
| D Welch Construction Limited | Construction | 2022 |
| D&C 7 Ltd | Construction | 2019 |
| D&D Property Holding Ltd | Real estate | 2018 |
| D-Mmex Limited | Wholesale & retail | 2003 |
| D-Scaffolding Ltd | Construction | 2023 |
| D.J.W. Electrical Engineering Limited | Construction | 2002 |
| D.S Investment Holdings Ltd. | Real estate | 2018 |
| D.T. Lofts Investment Ltd | Real estate | 2026 |
| D15H4 Consultancy Limited | Real estate | 2023 |
| D2 Venture Limited | Real estate | 2018 |
| D22 Hockey Academy Limited | Arts & recreation | 2022 |
| D4DAISY Books Limited | Information & communication | 2008 |
| D81 Ltd | Administrative & support | 2026 |
| Dablu Ltd | Transport & logistics | 2019 |
| DAC Tugulea Ltd | Construction | 2023 |
| Dacport Properties Limited | Construction | 2002 |
| Dadhugsgroup Ltd | Health & social care | 2025 |
| Daewoo Engineering & Construction Co., Ltd | | 2001 |
| Daintree Property Group Limited | Real estate | 2021 |
| Dakota Properties Ltd | Real estate | 2020 |
| Dalegrove Trading Limited | Construction | 2009 |
| Daleside Nursing Home Limited | Health & social care | 2005 |
| Dalm Consulting Ltd | Information & communication | 2017 |
| DAN Dediu Trans Ltd | Construction | 2019 |
| Dandelion Capital Ltd | Information & communication | 2024 |
| Dangerous Grounds Coffee Ltd | Hospitality | 2017 |
| Danielle Graham Productions Limited | Information & communication | 2012 |
| Daniels Roofing Ltd | Construction | 2026 |
| Dansan Ltd. | Real estate | 2019 |
| Dariawilliam Ltd | Transport & logistics | 2019 |
| Darvia Home Limited | Real estate | 2021 |
| Darvia Ltd | Wholesale & retail | 2021 |
| Darwin Wellness Limited | Arts & recreation | 2014 |
| Daryad Ltd | Information & communication | 2026 |
| Daso Ltd | Construction | 2000 |
| Data Cars Limited | Transport & logistics | 1999 |
| Data Cars Wolverhampton Limited | Information & communication | 2017 |
| Data Delta House Limited | Information & communication | 2023 |
| DATA2DECISION Consultancy Limited | Information & communication | 2010 |
| Dataconscious Group Limited | Information & communication | 2025 |
| Datatolia Ltd | Information & communication | 2025 |
| Dattani Associates Ltd | Professional & scientific | 2025 |
| Dattani Radiology Ltd | Health & social care | 2022 |
| Dattson Limited | Real estate | 2016 |
| David Bradnum Productions Limited | Information & communication | 1999 |
| David Brown England Ltd | Professional & scientific | 2017 |
| David Wilson Coaching Ltd | Health & social care | 2023 |
| Dawson Estates Limited | Real estate | 2003 |
| Dayspring Services Ltd | Professional & scientific | 2010 |
| Daze Commerce Limited | Wholesale & retail | 2022 |
| DB Data Solutions Ltd | Information & communication | 2015 |
| DB Mortgage Services Ltd | Financial services | 2015 |
| DBR Building Solutions Limited | Construction | 2024 |
| DBS3 Limited | Hospitality | 2017 |
| DC4ALL Ltd | Professional & scientific | 2024 |
| DCA Surveying Ltd | Real estate | 2024 |
| DCC SET Build & Construction Ltd | Manufacturing | 2025 |
| Dd-Crystal Ltd | Administrative & support | 2020 |