| City Select Academy Ltd | Education | 2023 |
| City Site Services Ltd | Administrative & support | 2016 |
| City Snacks Limited | Wholesale & retail | 2012 |
| City Vaperz Limited | Wholesale & retail | 2022 |
| City's Group Immigration Ltd | Professional & scientific | 2024 |
| City's Group Ltd | Professional & scientific | 2020 |
| Cityboxer.Com Limited | Arts & recreation | 2004 |
| Cityboy Chauffeurs Limited | Transport & logistics | 2024 |
| Cityedge Accountants Limited | Professional & scientific | 2006 |
| Cityfire Ltd | Construction | 2025 |
| Citygem Limited | Hospitality | 2023 |
| Cityline Autos Ltd | Wholesale & retail | 2026 |
| Citylink Recruitment Limited | Administrative & support | 2019 |
| Citylinks Properties Ltd | Real estate | 2022 |
| Citymile Estates Ltd | Real estate | 2004 |
| Citymile Services Ltd | Professional & scientific | 2016 |
| Citynestldn Ltd | Households | 2026 |
| Cityvale Finance Ltd | Professional & scientific | 2008 |
| Cityview Apartments (Chigwell) RTM Company Limited | Households | 2021 |
| Citywide UK Services Limited | Other services | 2019 |
| CJ Resin Ltd | Construction | 2024 |
| CJ Smart Solutions Ltd | Construction | 2025 |
| Cj&G Build Ltd | Construction | 2022 |
| CJE Consult Limited | Other services | 2012 |
| CJH Investments & Consulting Ltd | Information & communication | 2025 |
| CJN Concept Limited | Construction | 1990 |
| CJT Trading and Investments Ltd | Financial services | 2018 |
| CK HR Solutions Limited | Administrative & support | 2015 |
| CK Oneworld Ltd | Information & communication | 2026 |
| CK9 Security Services Ltd | Administrative & support | 2025 |
| Ckaur Services Ltd | Construction | 2025 |
| CKM Infrastructure Ltd | Construction | 2026 |
| CKS Property Investment Ltd | Real estate | 2010 |
| CKV Construction Ltd | Construction | 2024 |
| Clacton-On-Sea Properties Ltd | Real estate | 2022 |
| Claim Professionals Limited | Administrative & support | 2024 |
| Claimwise Group Limited | Administrative & support | 2024 |
| Claire Capital Ltd | Professional & scientific | 2020 |
| Claire Group Holdings Limited | Real estate | 2024 |
| Claire Real Estate Brokerage Ltd | Real estate | 2026 |
| Clairemonthomes Limited | Construction | 2016 |
| Clandon Care Limited | Real estate | 2009 |
| Clapton Glass and Joinery Limited | Construction | 2026 |
| Claredale Sheldon Limited | Other services | 2023 |
| Claremont Gardens Management Limited | Real estate | 2011 |
| Claremont Wines Limited | Professional & scientific | 1999 |
| Clarence Group Limited | Real estate | 2025 |
| Clarence Land & Homes Ltd | Real estate | 2024 |
| Clarence Point Ltd | Real estate | 2016 |
| Clarendon Hill Properties Ltd | Real estate | 2015 |
| Clarendon Luton Ltd | Real estate | 2022 |
| Claridons Ltd | Professional & scientific | 2020 |
| Claridons Venture Ltd | Real estate | 2022 |
| Clarion Homecare Ltd | Health & social care | 2022 |
| Clarion Logic Limited | Information & communication | 2012 |
| Clarity Sovereign Limited | Construction | 2024 |
| Clarkes Fruit & VEG Limited | Wholesale & retail | 2007 |
| Clarkes Stores Limited | Wholesale & retail | 2003 |
| Clarks Car Sales Ltd | Wholesale & retail | 2014 |
| Clas World Limited | Financial services | 2023 |
| Classic Cabinetry Designs Ltd | Manufacturing | 2020 |
| Classic Distributer and Suppliers Ltd | Transport & logistics | 2017 |
| Classic European Holidays Limited | Professional & scientific | 2017 |
| Classic Halal Foods Limited | Wholesale & retail | 2013 |
| Classic Jewellers Ltd | Wholesale & retail | 2023 |
| Classic London Limited | Wholesale & retail | 2018 |
| Classic Repairs Ltd | Transport & logistics | 2018 |
| Classic Textiles UK Ltd | Wholesale & retail | 2003 |
| Claudia Cristina Ltd | Other services | 2014 |
| Clausewise Limited | Professional & scientific | 2025 |
| Clay Bashing Limited | Extraterritorial | 2024 |
| Clay&Clan Limited | Wholesale & retail | 2025 |
| Claybridge Financial Planning Ltd | Financial services | 2009 |
| Claybury Bookkeeping & Co Ltd | Professional & scientific | 2019 |
| Claybury Estates Ltd | Professional & scientific | 2002 |
| Claybury Investments Limited | Real estate | 2015 |
| Claydrive Investments Ltd | Construction | 2014 |
| Clayhall Accounting Limited | Professional & scientific | 2014 |
| Clayhall Cleaning Services Ltd | Administrative & support | 2022 |
| Clayhall Osteopaths Ltd | Other services | 2015 |
| Clayhall Properties Ltd | Real estate | 2014 |
| Clayhall Property Services Ltd | Real estate | 2013 |
| Clayhall Services Ltd | Professional & scientific | 2021 |
| Claypark Capital Ltd | Real estate | 2026 |
| Clcd Limited | Construction | 2024 |
| Clean Master and Staff Solutions Ltd | Administrative & support | 2025 |
| CLEAN4TEAM Ltd | Administrative & support | 2020 |
| Cleanaura Ltd | Administrative & support | 2026 |
| Cleandone Ltd | Other services | 2014 |
| Cleaner Homz Ltd | Administrative & support | 2024 |
| Cleanify Cloth Limited | Other services | 2022 |
| Cleanjet Solutions Ltd | Administrative & support | 2025 |
| Clear Accountants and Tax Consultants Limited | Professional & scientific | 2020 |
| Clear Future Waste Ltd | Water & waste | 2026 |
| Clear OFF Ltd | Water & waste | 2021 |
| Clear Positive Change Ltd | Professional & scientific | 2023 |
| Clear Route Barakah CIC | Health & social care | 2026 |
| Clear to Hear Limited | Arts & recreation | 2012 |
| Clear Wave Therapy Ltd | Health & social care | 2026 |
| Clearance MNA Limited | Administrative & support | 2026 |