| Croy Chem Limited | Wholesale & retail | 1980 |
| Croydon Renovations Ltd | Construction | 2025 |
| CRT Events Ltd | Other services | 2022 |
| Crunch Pace Ltd | Wholesale & retail | 2022 |
| Crystal Rocks Properties Limited | Real estate | 2016 |
| Crystal VIZ Ltd | Information & communication | 2017 |
| Cucina Decorum Limited | Wholesale & retail | 2020 |
| Curio Learners Ltd | Education | 2025 |
| Curry House Purley Limited | Hospitality | 2019 |
| Curry on Naanstop Limited | Hospitality | 2017 |
| Curry on Naanstop Restaurants Limited | Hospitality | 2024 |
| CVD Legal Limited | Administrative & support | 2021 |
| Cyber Genesis X Ltd | Information & communication | 2024 |
| Cyber Security Hub Ltd | Information & communication | 2024 |
| Cyborg Limited | Information & communication | 1997 |
| D & J Property Investments Limited | Real estate | 2017 |
| D J Food Ltd. | Wholesale & retail | 2009 |
| D MAY Roofing Ltd | Construction | 2024 |
| D Sherwood Ltd | Manufacturing | 2019 |
| D&C Plumbing and Mechanical Ltd | Construction | 2026 |
| D&V Residentials Ltd. | Real estate | 2022 |
| D'Gama Limited | Real estate | 2013 |
| D-Oasis Limited | Health & social care | 2024 |
| D.M. Renovations Ltd | Construction | 2015 |
| D.R Digital Solutions Ltd | Information & communication | 2023 |
| D2 Print & Sign Limited | Professional & scientific | 2017 |
| Dahlia Homes Limited | Health & social care | 2014 |
| Dai-Ichi Lean Solutions Ltd. | Professional & scientific | 2012 |
| Dale Road RTM Company Limited | Households | 2020 |
| Daniel Robinson Financial Planning Limited | Professional & scientific | 2020 |
| Danielle Simone Design Ltd | Professional & scientific | 2025 |
| Darenace Ltd | Professional & scientific | 2017 |
| Darkwa Cleaning Ltd | Administrative & support | 2026 |
| Darnel Investments Limited | Professional & scientific | 1989 |
| Data DNA Ltd | Information & communication | 2017 |
| Data Privacy Management Consultants Limited | Professional & scientific | 2019 |
| David Bright Estates (Purley) Limited | Real estate | 2016 |
| Davis Property Consultants Limited | Real estate | 2024 |
| Dayalsons Limited | Real estate | 2025 |
| Daylook Ltd | Wholesale & retail | 2018 |
| Dazeaway Ltd | Administrative & support | 2020 |
| DB Chauffeurs Ltd | Transport & logistics | 2024 |
| Ddig Electrical and Testing Services Limited | Construction | 2023 |
| Deacons Standen Consultants Limited | Professional & scientific | 2002 |
| Dean Aston Advisory Ltd | Information & communication | 2022 |
| Deansgate Co-Ordination Services Limited | Professional & scientific | 2022 |
| Deboss Enterprise Ltd | Real estate | 2025 |
| Decision Stream Limited | Other services | 2000 |
| Delegateuk Limited | Extraterritorial | 2012 |
| Delivery Evolved Limited | Information & communication | 2024 |
| Denali's Cleaning Services Ltd | Administrative & support | 2025 |
| Densham Drive Limited | Households | 2012 |
| Denteways Ltd | Mining & quarrying | 2018 |
| Desert Highway Productions Ltd | Information & communication | 2021 |
| Design and Construction Traders Ltd | Construction | 2021 |
| Design Extension BC Ltd | Professional & scientific | 2025 |
| Design Extension Ltd | Professional & scientific | 2025 |
| Design Your Trends Limited | Wholesale & retail | 2020 |
| Destine Solutions Limited | Health & social care | 2013 |
| Developaproperty Ltd | Real estate | 2014 |
| Devoiray Limited | Financial services | 2024 |
| Devsena Limited | Real estate | 2021 |
| Dfstructures Limited | Construction | 2026 |
| DGB Edwards Limited | Professional & scientific | 2026 |
| Different IS Good Limited | Wholesale & retail | 2019 |
| Differenxia Consulting Ltd | Professional & scientific | 2013 |
| Digital Arts Xchange Ltd | Manufacturing | 2023 |
| Digital PDF Solutions Ltd | Information & communication | 2025 |
| Digitalflakes Ltd | Other services | 2015 |
| DIH Consulting Limited | Administrative & support | 2007 |
| Dinocreatives Limited | Professional & scientific | 2023 |
| DIP International Limited | Wholesale & retail | 1994 |
| DIP Trustees Limited | Professional & scientific | 2003 |
| Director Verify Ltd | Professional & scientific | 2025 |
| Dismed Limited | Wholesale & retail | 2014 |
| Dixon Works Ltd | Construction | 2026 |
| Djuvuj Ltd | Information & communication | 2026 |
| DNA Consulting Limited | Professional & scientific | 2022 |
| DNA Travel Limited | Administrative & support | 2025 |
| DOC Transport Limited | Transport & logistics | 2013 |
| Doctivate Limited | Health & social care | 2017 |
| Does the JOB Ltd | Wholesale & retail | 2014 |
| Donrone Properties Limited | Real estate | 2005 |
| Downer Associates Ltd | Administrative & support | 2021 |
| Downlands IT Solutions Limited | Information & communication | 2017 |
| DOY Edward Street Management Limited | Households | 2024 |
| Dpdf Ltd | Construction | 2025 |
| DR Beth Aesthetics Ltd | Other services | 2023 |
| DR JS Medical Limited | Health & social care | 2012 |
| DR Y K Patel Ltd | Real estate | 2014 |
| Dragon Purley Ltd | Hospitality | 2022 |
| Dresslana Ltd | Manufacturing | 2016 |
| Drift Academy & Media CIC | Information & communication | 2025 |
| Drift Escapes Ltd | Hospitality | 2025 |
| Drifters Properties Limited | Real estate | 2005 |
| Drtan Limited | Health & social care | 2025 |
| Drunas Consulting Ltd | Information & communication | 2017 |
| DS Lifestyle Limited | Wholesale & retail | 2017 |
| DS Sales Contracting Ltd | Professional & scientific | 2024 |
| Dskincode Kosmetics Limited | Wholesale & retail | 2025 |