| COZ Holdings Limited | Financial services | 2026 |
| CPS Builds Ltd | Construction | 2026 |
| Cpts Solutions Limited | Administrative & support | 2025 |
| CR5 Limited | Real estate | 2024 |
| Crack the Code Worldwide Ltd | Arts & recreation | 2025 |
| Craft & Law Ltd | Professional & scientific | 2026 |
| Craton Ltd | Real estate | 2018 |
| Cream Properties Limited | Construction | 2018 |
| Creative Property LAB Limited | Real estate | 2019 |
| Creative Surface Finishes Ltd | Construction | 2020 |
| Creator Scale Academy Ltd | Information & communication | 2025 |
| Creek House Residents' Association Limited | Households | 1996 |
| Creogence Ltd | Wholesale & retail | 2017 |
| Crescent View Management Company Limited | Households | 1994 |
| Crespa SIM Ltd | Wholesale & retail | 2022 |
| Crestmere Properties Ltd | Real estate | 2024 |
| Crew & Co Limited | Wholesale & retail | 2013 |
| Crews Hill Nurseries Ltd | Wholesale & retail | 2019 |
| Cristal Cleaners Limited | Administrative & support | 2023 |
| Cristina Gatu Studios Ltd | Information & communication | 2021 |
| Crossfold Electrical Wholesalers Limited | Wholesale & retail | 1982 |
| Crosswise Limited | Information & communication | 2013 |
| Crow Metals Limited | Water & waste | 2004 |
| Crown Central Limited | Real estate | 2003 |
| Crown Chauffeur Drive UK Limited | Transport & logistics | 2009 |
| Crown House Investments Limited | Real estate | 2016 |
| Crown of India Ltd | Hospitality | 2023 |
| Croxbridge Limited | Financial services | 2022 |
| CRS1 Ltd | Wholesale & retail | 2020 |
| Crush Cocktail Bar Ltd | Administrative & support | 2014 |
| Crystal Applied Services Limited | Construction | 2017 |
| Crystal Properties & Investments Ltd | Administrative & support | 2008 |
| CS Hvac Limited | Energy | 2008 |
| CS Operations Ltd | Other services | 2021 |
| CSI: Maintenance Ltd | Construction | 2013 |
| Csmh Limited | Administrative & support | 2025 |
| CT Fast Food Service Limited | Hospitality | 2024 |
| Cti-Crm Limited | Information & communication | 2000 |
| Cube Blue Investment Limited | Construction | 2020 |
| Cube Green Investment Limited | Construction | 2020 |
| Cube Orange Investment Limited | Construction | 2020 |
| Cube Properties (Essex) Ltd | Real estate | 2025 |
| Cube Quantity Surveying Limited | Professional & scientific | 2019 |
| Cube Red Investment Limited | Construction | 2020 |
| Cubic Retail Limited | Real estate | 2017 |
| Cubital Limited | Professional & scientific | 2023 |
| Cuffley Construction Ltd | Construction | 2020 |
| Cult Pilates Ltd | Health & social care | 2023 |
| Cummins Properties Limited | Real estate | 2021 |
| Curious Catering Ltd | Hospitality | 2020 |
| Currie Health Ltd | Wholesale & retail | 2023 |
| Curtis Chambers Equestrian Ltd | Agriculture & fishing | 2023 |
| Cushdy Cosmetics Ltd | Other services | 2021 |
| CUT Above Landscapers Limited | Administrative & support | 2020 |
| CUT Above Tree Care Limited | Administrative & support | 2020 |
| CWS Care Ltd | Administrative & support | 2023 |
| CWS Jobs Ltd | Administrative & support | 2025 |
| Cyber Computer Consultants Limited | Real estate | 1993 |
| D & E Properties Ltd | Real estate | 2023 |
| D Best Waste Limited | Water & waste | 2024 |
| D Costa Property Developments Ltd | Real estate | 2015 |
| D Cotton Services Limited | Professional & scientific | 2021 |
| D F Credit Services Limited | Financial services | 1994 |
| D Gardener Maintenance Ltd | Real estate | 2025 |
| D Meta Construction Limited | Construction | 2022 |
| D T G R Ltd | Real estate | 2015 |
| D T P Acquisitions Ltd | Real estate | 2008 |
| D T Property Services Ltd | Financial services | 2004 |
| D&A Cleaning Solutions Limited | Administrative & support | 2017 |
| D&C World Services Ltd | Administrative & support | 2020 |
| D&D Dynamics Ltd | Hospitality | 2026 |
| D&D Entrepreneur Ltd | Real estate | 2024 |
| D&R Investment Properties LLP | | 2018 |
| D&T Mechanical Pipeworks Solutions Limited | Construction | 2019 |
| D-Providence Ltd | Real estate | 2024 |
| D-Stax Limited | Information & communication | 2023 |
| D-Tech Electrical Services Limited | Construction | 1997 |
| D. Cawley & Sons Limited | Construction | 1985 |
| D.C. Morgan & Co. Limited | Transport & logistics | 1963 |
| D.C.R UK Services Ltd | Wholesale & retail | 2019 |
| D3 Urban Planning Ltd | Professional & scientific | 2014 |
| DA Productions International Ltd | Information & communication | 2026 |
| DAC Management Limited | Professional & scientific | 2016 |
| Dach One Ltd | Construction | 2026 |
| DAE Capital Management Limited | Professional & scientific | 2018 |
| Daego Limited | Professional & scientific | 2013 |
| Dahlia Health & Wellness Ltd | Wholesale & retail | 2026 |
| Daipol Ltd | Financial services | 2022 |
| DAK Elite Services Ltd | Construction | 2013 |
| Daley Grey Limited | Real estate | 2024 |
| Dalima Limited | Information & communication | 2020 |
| Dalton Properties Limited | Construction | 2011 |
| DAM Investments Limited | Construction | 2001 |
| DAM Property Trading Limited | Real estate | 2021 |
| Daman Holdings Ltd | Construction | 2019 |
| Dames Hall Corner Limited | Real estate | 2003 |
| Damyan 87 Ltd | Hospitality | 2019 |
| Danaila Construction Management Ltd | Construction | 2018 |
| Danbury Lodge Limited | Households | 2000 |
| Danmil Style Ltd | Real estate | 2018 |