| City Cleaning and Removing Ltd | Other services | 2021 |
| City Cleaning Service Ltd | Administrative & support | 2015 |
| City Conscierge Services Ltd | Professional & scientific | 2024 |
| City Consultancy Services Ltd | Administrative & support | 2017 |
| City Country Coast Ltd | Real estate | 2019 |
| City D&B Ltd | Construction | 2014 |
| City Fashion Limited | | 2000 |
| City FI Limited | Wholesale & retail | 2002 |
| City FM Group Limited | Financial services | 2025 |
| City Horizon Limited | Professional & scientific | 2018 |
| City Hotel Rooms (London) LLP | | 2011 |
| City Hotel Rooms Limited | Administrative & support | 2001 |
| City Kitchen London UK Limited | Administrative & support | 2016 |
| City Legal Services Limited | Professional & scientific | 2014 |
| City of London Properties Ltd | Real estate | 2024 |
| City Property Developers Limited | Real estate | 2003 |
| City Real Estate Holdings Limited | Real estate | 2025 |
| City Tech Business Solutions Ltd | Information & communication | 2015 |
| City Tiler Group Ltd | Construction | 2019 |
| City Venture Group Ltd | Professional & scientific | 2023 |
| Citycis Ltd | Other services | 2021 |
| Cityclean Service.Com Ltd | Administrative & support | 2024 |
| Cityfly Limited | Administrative & support | 2014 |
| Cityride Express Ltd | Transport & logistics | 2026 |
| Citywest.Co.Uk Limited | Real estate | 2007 |
| Cityworx Limited | Administrative & support | 2007 |
| Ciulii Ltd | Transport & logistics | 2018 |
| Ciulo Limited | Construction | 2024 |
| Ciurea Limited | Construction | 2025 |
| Civicare Central Limited | Health & social care | 2000 |
| CJ & Triple R Limited | Real estate | 2024 |
| CJ Capital Corp. Ltd | Wholesale & retail | 2022 |
| CJ Care Services Ltd | Health & social care | 2018 |
| CJ Global Consulting Ltd | Professional & scientific | 2025 |
| CJ One Holdings Limited | Professional & scientific | 2025 |
| CJ Pilates and Nutrition Limited | Health & social care | 2025 |
| CJ Smiles Limited | Health & social care | 2024 |
| CJ Trade Links (UK) Ltd | Wholesale & retail | 2022 |
| Cj&J Property Trading Limited | Real estate | 2016 |
| CJA Business Solutions Ltd | Information & communication | 2017 |
| CJK Consultants Limited | Administrative & support | 2004 |
| CJK IM Ltd | Information & communication | 2024 |
| CJK Investment Properties Limited | Real estate | 2020 |
| CJM Estate Ltd | Real estate | 2015 |
| CJM Operations Ltd | Construction | 2025 |
| CJM Properties London Ltd | Real estate | 2017 |
| CJO Enterprise Limited | Hospitality | 2013 |
| Cjrg Limited | Real estate | 2025 |
| CJT Promotions Limited | Arts & recreation | 2018 |
| CK Constructions and Development Ltd | Construction | 2016 |
| CK Global Advisory Co. Ltd | Professional & scientific | 2024 |
| CK Retail Stores Ltd | Professional & scientific | 2025 |
| CK Whelan Ltd | Construction | 2026 |
| CK7 Investments Limited | Real estate | 2019 |
| CKG Holdings Ltd | Financial services | 2026 |
| CKG OT Limited | Health & social care | 2017 |
| Ckmd Consultancy Ltd | Professional & scientific | 2026 |
| Ckrokeby Property Ltd | Real estate | 2026 |
| CKS Property & Land Investments Ltd | Real estate | 2022 |
| Ckstation Property Ltd | Real estate | 2026 |
| CL Convenience Store Ltd | Wholesale & retail | 2021 |
| CL3ANLAB Limited | Administrative & support | 2020 |
| CLA Family Care Ltd | Health & social care | 2026 |
| Claimok Ltd | Information & communication | 2018 |
| Claire Jackman Limited | Health & social care | 2014 |
| Claire Mcintosh Limited | Other services | 2009 |
| Clamp Investment Co Ltd | Real estate | 2013 |
| Clanricarde Consulting Limited | Financial services | 2015 |
| Clap Box Limited | Administrative & support | 2025 |
| Clar Consultants Ltd | Administrative & support | 2017 |
| Claremont Construction Holdings Ltd | Financial services | 2025 |
| Claremont Construction Ltd | Professional & scientific | 2019 |
| Claremont Global Limited | Hospitality | 2021 |
| Claremont Refurbishment Ltd. | Construction | 1986 |
| Clarence Estates (London) Limited | Construction | 1984 |
| Clarence Grays RTM Company Limited | Real estate | 2008 |
| Clarendon Financial Marketing Ltd | Professional & scientific | 2015 |
| Clarendon House Care Holdings Limited | Health & social care | 2016 |
| Clarendon House Care Limited | Health & social care | 2015 |
| Clarendon Information Systems Limited | Professional & scientific | 1996 |
| Claresta Hotels Blackpool Ltd | Hospitality | 2025 |
| Clarewood RA Limited | Real estate | 2022 |
| Clarewood SA Limited | Real estate | 2024 |
| Clarges Street Limited | Real estate | 2022 |
| Claritas Books Ltd | Information & communication | 2017 |
| Clarity Consulting Services Limited | Professional & scientific | 2025 |
| Clarity LK Limited | Health & social care | 2020 |
| Clarity Property Development LLP | | 2016 |
| Clarity RE LLP | | 2018 |
| Claritybuild Limited | Construction | 2025 |
| Clarium Managed Services Ltd | Information & communication | 2021 |
| Clark Masts Systems Limited | Manufacturing | 1979 |
| Clark Masts Teksam Limited | Manufacturing | 1979 |
| Clark White Publishing Limited | Information & communication | 2003 |
| Clarkes Associate Consultancy Ltd | Real estate | 2018 |
| Clarksmill Limited | Professional & scientific | 2022 |
| Clarom Ltd | Wholesale & retail | 2014 |
| Clarum Consulting Ltd | Information & communication | 2018 |
| Class Motors Limited | Wholesale & retail | 2026 |
| Class of Magic Limited | Administrative & support | 2015 |