| Csgc Logistics Ltd | Transport & logistics | 2024 |
| CSM Consultants Limited | Professional & scientific | 2012 |
| CSN Enterprises Limited | Information & communication | 2016 |
| CSN Group Holdings Limited | Real estate | 2021 |
| CSN Technical Solutions Limited | Information & communication | 2020 |
| Cszmyers Ltd | Construction | 2025 |
| Ctpl Electrical Limited | Construction | 2010 |
| Ctsris Healthcare Ltd | Health & social care | 2026 |
| Cuadro Art Ltd | Wholesale & retail | 2014 |
| Cubani Properties Limited | Real estate | 2019 |
| Cubberley-Gomis FP Limited | Professional & scientific | 2017 |
| Cubedevelop Ltd | Construction | 2019 |
| Cubic Zirconium Foundation Limited | Education | 2001 |
| Cuce Property Management Ltd | Real estate | 2024 |
| CUE Point Crew Limited | Administrative & support | 2025 |
| Cuffe Parade Capital Partners Limited | Professional & scientific | 2018 |
| Cujba Coachworks Limited | Manufacturing | 2024 |
| Cujes Global Ltd | Construction | 2020 |
| Culai & Sons Ltd | Construction | 2018 |
| Culling's Health and Safety Limited | Professional & scientific | 2022 |
| Culmination Magazine Ltd | Professional & scientific | 2023 |
| CUP Cloud Ltd | Hospitality | 2024 |
| Curchin Ltd | Manufacturing | 2022 |
| Curious on Purpose Ltd | Professional & scientific | 2024 |
| Curlflow Ltd | Manufacturing | 2025 |
| Curtismill Holsteins Limited | Agriculture & fishing | 2023 |
| Cushla Francis Design and Photography Limited | Professional & scientific | 2017 |
| Custom Capsules Ltd | Health & social care | 2023 |
| Custom Estate Ltd | Extraterritorial | 2023 |
| Custom Heating Limited | Construction | 2008 |
| Custom Pets Portraits Ltd | Arts & recreation | 2025 |
| Customate Kids Ltd | Wholesale & retail | 2026 |
| Customer Centric Services Ltd | Information & communication | 2025 |
| Customville Ltd | Wholesale & retail | 2005 |
| Cute Girl UK Limited | Manufacturing | 2017 |
| Cutting Hedge Television Limited | Information & communication | 2009 |
| Cutts (Bromley) Limited | Real estate | 1954 |
| Cvbv Ltd | Information & communication | 2025 |
| Cvcs Construct Ltd | Construction | 2017 |
| CVI Heating & Plumbing Ltd | Construction | 2026 |
| CVL Windscreens Ltd | Wholesale & retail | 2026 |
| CVS Construction Limited | Construction | 2015 |
| CVV Transport Couriers Ltd | Transport & logistics | 2020 |
| CWB Services (Romford) Limited | Water & waste | 2020 |
| Cwcs Holdings Limited | Financial services | 2023 |
| CWI (London) Limited | Construction | 2014 |
| CWI Facades Limited | Construction | 2024 |
| CWP Management Services Ltd | Administrative & support | 2025 |
| CXM AB Ltd | Construction | 2026 |
| CXO Consulting Limited | Extraterritorial | 2015 |
| CXO Couriers Ltd | Extraterritorial | 2018 |
| CY Concept Services Ltd | Health & social care | 2022 |
| Cyan Consultancy Ltd | Information & communication | 2016 |
| Cyber Comms Limited | Professional & scientific | 2021 |
| Cyber Cover Ltd | Financial services | 2017 |
| Cyber Vida Limited | Information & communication | 2025 |
| Cybergrowth-Media Ltd | Professional & scientific | 2023 |
| Cyberknight Recruitment Ltd | Administrative & support | 2023 |
| Cybersentinel Dynamics Ltd | Wholesale & retail | 2024 |
| Cybertechnology Management & Legal Services Limited | Professional & scientific | 2012 |
| Cyp&Andra Ltd | Transport & logistics | 2019 |
| CYS Windows Ltd | Construction | 2019 |
| Cyta Security and Facilities Management Ltd | Administrative & support | 2026 |
| Cytrax IT Solutions Limited | Information & communication | 2014 |
| D & D Patel Limited | Wholesale & retail | 2015 |
| D & D Roofers Limited | Construction | 2016 |
| D & G Property Solutions LLP | | 2014 |
| D & K Gandhi Ltd | Real estate | 2020 |
| D and G Consult Properties Ltd | Real estate | 2026 |
| D C Bodyworks Limited | Wholesale & retail | 2011 |
| D C Tape Interior's Limited | Construction | 2019 |
| D E Ventilation Limited | Construction | 2019 |
| D Holland Limited | Professional & scientific | 2012 |
| D Moreno Limited | Construction | 2024 |
| D Patry Building Ltd | Construction | 2021 |
| D Square Estates Limited | Real estate | 2021 |
| D W Hardy Ltd | Professional & scientific | 2014 |
| D W Peacock Ltd | Professional & scientific | 2018 |
| D Wells Limited | Wholesale & retail | 2006 |
| D&A Delivery Services Ltd | Transport & logistics | 2019 |
| D&B Accountancy Services Ltd | Other services | 2017 |
| D&B Investment Step Ltd | Real estate | 2018 |
| D&Caitlin Ltd | Administrative & support | 2026 |
| D&D Builders Team Ltd | Construction | 2019 |
| D&D Constructions Works Ltd | Construction | 2022 |
| D&D Hill Ltd | Hospitality | 2025 |
| D&D Mechanical Solutions Ltd | Construction | 2026 |
| D&D Privilege Limited | Construction | 2015 |
| D&D Site Services Limited | Professional & scientific | 2025 |
| D&D Transport Logistics Ltd | Transport & logistics | 2018 |
| D&F Drylining Ltd | Construction | 2018 |
| D&G International Limited | Administrative & support | 2012 |
| D&I Events Services Ltd | Administrative & support | 2021 |
| D&J London Property Limited | Real estate | 2020 |
| D&K Brickwork Ltd | Construction | 2025 |
| D&Kg Cat Construction Limited | Construction | 2018 |
| D&M Mechanical Engineering Service Limited | Manufacturing | 2012 |
| D&N Buildworks Ltd | Construction | 2025 |
| D&N Trade Limited | Wholesale & retail | 2025 |
| D&Pk News Limited | Wholesale & retail | 2020 |