| Crossley Field Consulting Ltd | Other services | 2017 |
| Crossway (Bromley) Freehold Limited | Households | 2023 |
| Crossways (Slough) Management Company Limited | Households | 2016 |
| Crossways Garage (Bromley) Ltd | Wholesale & retail | 2011 |
| Crowdbit Academy Limited | Other services | 2025 |
| Crowdgainer Ltd | Financial services | 2022 |
| Crowfoot Films Limited | Information & communication | 2002 |
| Crown and Anchor Bromley Ltd | Hospitality | 2018 |
| Crown and Bullion Ltd | Wholesale & retail | 2025 |
| Crown Court Bromley Residents Limited | Households | 2007 |
| Crown Heart Facades Ltd | Construction | 2023 |
| Crown Properties London Limited | Administrative & support | 2022 |
| Crown Stitch Tailoring Ltd | Manufacturing | 2026 |
| Crown Your Beauty London Limited | Other services | 2014 |
| Crowndale Developments (London) Limited | Construction | 2014 |
| Crownpoint Surveyors Ltd | Real estate | 2026 |
| Crownshield Locksmiths Ltd | Manufacturing | 2021 |
| Croydon Car Spares Limited | Real estate | 1958 |
| CRP Brickwork Ltd | Construction | 2025 |
| CRS Advisory Limited | Administrative & support | 2024 |
| CRS Hair and Beauty Ltd | Other services | 2023 |
| Crucial Analytics Limited | Professional & scientific | 2010 |
| Crucial Analytics Technology Limited | Professional & scientific | 2011 |
| Crucial Systems Limited | Professional & scientific | 2015 |
| Crucial Technology Limited | Professional & scientific | 2011 |
| Crus Supreme Ltd | Wholesale & retail | 2020 |
| Cryptosphere Limited | Information & communication | 2007 |
| Crystal Clear Coaching Limited | Health & social care | 2023 |
| Crystal Palace Group Limited | Other services | 2026 |
| CS Design Studio Ltd | Professional & scientific | 2024 |
| CS Development & Consultancy Services Limited | Financial services | 2022 |
| CS Property Build Ltd | Real estate | 2026 |
| CSC Plumbing Ltd | Construction | 2020 |
| Csiga Ltd | Information & communication | 2015 |
| Cssm Property Services Ltd | Real estate | 2025 |
| Cstuninguk Ltd | Wholesale & retail | 2024 |
| CTC Consulting International Limited | Professional & scientific | 2021 |
| CTC Heating Services Limited | Construction | 2013 |
| CTK Developments Ltd | Construction | 2026 |
| CTK Freehold Co Ltd | Professional & scientific | 2025 |
| CTK Homes Ltd | Real estate | 2020 |
| CTK Property Group Ltd | Financial services | 2025 |
| Ctld Holdings Limited | Administrative & support | 2025 |
| Cube EV Chargers Ltd | Manufacturing | 2022 |
| CUE Solutions Ltd | Information & communication | 2019 |
| Cultcaine Records Ltd | Information & communication | 2026 |
| Cultural Transitions CIC | Professional & scientific | 2012 |
| Culture Fitt Ltd | Professional & scientific | 2023 |
| Cumberlow Lodge Management Company Limited | Households | 2010 |
| Cumero Cars UK Ltd | Wholesale & retail | 2024 |
| Cuppo Bubbo Operations Ltd | Hospitality | 2026 |
| Curious Crab Productions Limited | Information & communication | 2025 |
| Curious Ferret Limited | Information & communication | 2009 |
| Curious in London Ltd | Administrative & support | 2022 |
| Curtis and Cavendish Builders Limited | Construction | 2007 |
| Curve Water Limited | Wholesale & retail | 2025 |
| Cutty Sark MOT & Service Centre Limited | Wholesale & retail | 2019 |
| Cutty Sharp Ltd | Other services | 2019 |
| CV Artists Limited | Arts & recreation | 1996 |
| CW Recruits Limited | Administrative & support | 2005 |
| CWA (Beckenham) Limited | Professional & scientific | 2008 |
| Cwilson Properties Ltd | Real estate | 2019 |
| CWS (Chattaway Wealth Services) Ltd | Financial services | 2025 |
| Cyan Spaces Limited | Real estate | 2021 |
| Cyber Assuranze Limited | Administrative & support | 2023 |
| Cyber Mercenaries Ltd | Professional & scientific | 2025 |
| Cyber Threat Intelligence Board - Ctib Ltd | Other services | 2026 |
| Cyber-Train Limited | Education | 2025 |
| Cyberhouse Corporation Limited | Information & communication | 2005 |
| Cybersec Europe Ltd | Administrative & support | 2017 |
| Cybrosys Limited | Information & communication | 2017 |
| Cynosure Media Ltd | Wholesale & retail | 2025 |
| Cypress District Energy Holdco Limited | Financial services | 2023 |
| Cypress District Energy Limited | Financial services | 2023 |
| Cypress UK Holdco (UK) Limited | Financial services | 2023 |
| Cyreel Ltd | Wholesale & retail | 2025 |
| D & P Potter Rigging Services Ltd | Construction | 2020 |
| D a a Homes Ltd | Real estate | 2021 |
| D a Upcraft Limited | Administrative & support | 2018 |
| D H Home Construction Limited | Administrative & support | 2017 |
| D Hall Carpentry and Building Services Ltd | Construction | 2019 |
| D Kent Holdings Limited | Financial services | 2025 |
| D Lamoon Site Management Limited | Public administration | 2014 |
| D Life Trac Limited | Extraterritorial | 2023 |
| D Lother Medical Ltd | Health & social care | 2023 |
| D Mills Carpentry Ltd | Construction | 2023 |
| D P L Limited | Manufacturing | 1983 |
| D Peters Estates Ltd | Real estate | 2022 |
| D X Investments Ltd | Financial services | 2016 |
| D&A Group (London) Ltd | Wholesale & retail | 2026 |
| D&Aa Limited | Other services | 2014 |
| D&B Academy of Performing Arts Limited | Education | 2018 |
| D&D Rendering Ltd | Construction | 2026 |
| D&F Developments Ltd | Construction | 2023 |
| D&J Consulting Ltd | Professional & scientific | 2024 |
| D&J Private Hire Ltd | Transport & logistics | 2019 |
| D&M Financial Services (UK) Limited | Professional & scientific | 2014 |
| D&R Tutoring Services CIC | Education | 2020 |
| D&T Building Ltd | Construction | 2015 |
| D&T General Construction Ltd | Construction | 2024 |