| Capital Waterproofing Ltd | Construction | 2018 |
| CAR2SHIP Ltd | Administrative & support | 2012 |
| Carbonitalia UK Ltd | Wholesale & retail | 2021 |
| Carbonnano Ltd. | Manufacturing | 2015 |
| Cardinals Freeholders Limited | Real estate | 2022 |
| Cargo Labels Limited | Wholesale & retail | 2004 |
| Castle Retro Ltd | Wholesale & retail | 2026 |
| Cataleya Ioana Transport Ltd | Transport & logistics | 2021 |
| Catlyng Limited | Financial services | 2025 |
| Catmor Properties Ltd | Real estate | 2025 |
| CAV Trans Limited | Transport & logistics | 2015 |
| Cedar Software Solutions Ltd | Information & communication | 1985 |
| Central Transilvania Ltd | Transport & logistics | 2024 |
| CES Trans Limited | Transport & logistics | 2019 |
| Cezar Driver UK Ltd | Transport & logistics | 2023 |
| CGI Gardening Ltd | Transport & logistics | 2025 |
| Chaos Boxing Equipment Ltd | Administrative & support | 2017 |
| Charles JAY Haulage Ltd | Transport & logistics | 2013 |
| Chevalier (2015) Ltd | Professional & scientific | 2015 |
| Cheveley Freehold Limited | Real estate | 2022 |
| Chidlowproducts Ltd | Wholesale & retail | 2023 |
| Chirita Ltd | Transport & logistics | 2015 |
| Circable Ltd | Arts & recreation | 2025 |
| Ciukauk. Ltd | Transport & logistics | 2017 |
| CJN Trading Ltd | Wholesale & retail | 2025 |
| Claremont Developments (Essex) Limited | Real estate | 1980 |
| Clarion Shipping and Logistics UK Ltd | Transport & logistics | 2022 |
| Clean JOB Limited | Transport & logistics | 2025 |
| Cleaning Connection Ltd | Administrative & support | 2024 |
| Clikk Management Ltd | Professional & scientific | 2016 |
| Cloudnet Consultancy Ltd | Information & communication | 2013 |
| CML Maintenance Ltd | Construction | 2024 |
| CNN Sports Research Ltd | Wholesale & retail | 2026 |
| Coastal Accountancy Ltd | Professional & scientific | 2022 |
| Coastal Bookkeeping & Payroll Limited | Professional & scientific | 2024 |
| Coastal Bookkeeping (Suffolk) Limited | Professional & scientific | 2022 |
| Coastal Global Logistics Limited | Transport & logistics | 2006 |
| Coastal Global Services Limited | Transport & logistics | 2013 |
| Coastal Trail Runners Ltd | Arts & recreation | 2024 |
| Coastside Windows Limited | Construction | 2013 |
| Cobbold Court (Felixstowe) Limited | Hospitality | 2005 |
| Cognitive Autonomy Ltd | Information & communication | 2026 |
| Cole and Carr Limited | Hospitality | 2019 |
| Collanature Ltd | Manufacturing | 2025 |
| COM - Bine.Com Limited | Professional & scientific | 2008 |
| Community Active & Wellbeing CIC | Education | 2024 |
| Compare the Annuity Limited | Financial services | 2020 |
| Compare the Utility Limited | Extraterritorial | 2020 |
| Computing Needs Limited | Wholesale & retail | 1998 |
| Comtrans BNI Ltd | Transport & logistics | 2026 |
| Concord Asia Limited | Transport & logistics | 2004 |
| Conexim Solutions Ltd | Transport & logistics | 2015 |
| Conkers Pets Ltd | Wholesale & retail | 2011 |
| Connected Logistics Ltd | Transport & logistics | 2023 |
| Consolidation Express Cargo Limited | Transport & logistics | 2022 |
| Constable Contractors Ltd | Construction | 2015 |
| Constantin Popescu Ltd | Transport & logistics | 2018 |
| Continuity Consulting Ltd | Information & communication | 2002 |
| Cookie Barista (Felixstowe) Ltd | Hospitality | 2023 |
| Cooking Vinyl Publishing Limited | Information & communication | 2007 |
| Cooks Workshop Ltd | Manufacturing | 2026 |
| Cordy Associates Limited | Education | 2017 |
| Coriander Close 1967 Limited | Extraterritorial | 2015 |
| Crafty Consultancy Ltd | Administrative & support | 2022 |
| Crafty Grandma Ltd | Manufacturing | 2025 |
| Crafty Lasty Cafe Ltd | Other services | 2018 |
| Crafty Lasty Yarn Ltd | Wholesale & retail | 2021 |
| Crecca Limited | Administrative & support | 2009 |
| Cremanaru Transport Ltd | Transport & logistics | 2019 |
| Crisp & Dene Ltd | Manufacturing | 2012 |
| Crofts Timber Limited | Wholesale & retail | 2009 |
| Crystal Finish Valeting Limited | Administrative & support | 2026 |
| Cumberland Investments (Woodbridge) Limited | Real estate | 2007 |
| Cuppa Communitea C.I.C. | Hospitality | 2025 |
| Customs Support Group UK Limited | Financial services | 2021 |
| Cvcuk Limited | Transport & logistics | 2012 |
| Cvsurfers Ltd | Administrative & support | 2023 |
| Cyber Defence Dynamics Ltd | Information & communication | 2013 |
| Cyty Ciuguzel Ltd | Transport & logistics | 2024 |
| D G Masters Ltd | Transport & logistics | 2017 |
| D H Freight Ltd | Transport & logistics | 2015 |
| D&M Global Solutions Limited | Extraterritorial | 2023 |
| D&M Logistic Solutions Limited | Transport & logistics | 2011 |
| D. Joco Transports Ltd | Administrative & support | 2014 |
| D.J.B. Haulage Ltd. | Transport & logistics | 1997 |
| DA Vinci Limited | Professional & scientific | 2008 |
| Dailyfresh Logistics | | 1999 |
| Damileanu Transport Ltd | Transport & logistics | 2020 |
| DAN CH Trans Limited | Transport & logistics | 2020 |
| Daniel Read TM Ltd | Construction | 2024 |
| Danoble Developments Limited | Construction | 2014 |
| Dany 96 Limited | Transport & logistics | 2025 |
| Dariusz Arbudzinski Ltd | Transport & logistics | 2012 |
| Darth Redvers Ltd | Administrative & support | 2017 |
| Darth Redvers Property Ltd | Real estate | 2021 |
| Dawid Najzer Transport (DNT) Ltd | Transport & logistics | 2016 |
| Day Financial Planning Ltd | Financial services | 2016 |
| DB Music Sales Limited | Administrative & support | 2003 |
| DCS Freight UK Limited | Transport & logistics | 2017 |
| DE Rijke Intermodal (UK) Ltd | Transport & logistics | 1973 |