| Chime Music CIC | Health & social care | 2021 |
| Chivers Accounting Limited | Professional & scientific | 2009 |
| Chloe Reynolds Property Ltd | Real estate | 2019 |
| CHM Works Ltd | Professional & scientific | 2026 |
| Chmbrs Ltd | Information & communication | 2023 |
| Choi Empire Limited | Hospitality | 2026 |
| Choice Language Services Limited | Extraterritorial | 2000 |
| Chopup Limited | Hospitality | 2023 |
| Choudhury CP Ltd | Real estate | 2025 |
| Choudhury Properties Limited | Real estate | 2025 |
| Chris Allen Estate Agent Limited | Real estate | 2021 |
| Chris Hodson Business Development Limited | Professional & scientific | 2011 |
| Chris Regan Limited | Professional & scientific | 2006 |
| Chris Wilson Felt-Asphalt Limited | Construction | 2001 |
| Christopher B Long Ltd | Wholesale & retail | 2019 |
| Christy Cooling Services Limited | Construction | 1998 |
| Chrome Centre Ltd | Wholesale & retail | 2017 |
| Chrome Chasers Ltd | Administrative & support | 2025 |
| Chronos International Group Ltd | Financial services | 2024 |
| Chronos IT Services Ltd | Information & communication | 2024 |
| Chrysalis Public Relations Limited | Information & communication | 2005 |
| Chrysalis Systems Ltd | Information & communication | 2016 |
| CHS Engineering Services Ltd | Other services | 2022 |
| Chubbytiger & Co. Limited | Real estate | 2018 |
| Chudley Online Limited | Professional & scientific | 2021 |
| Chukobi Consultancy Limited | Professional & scientific | 2021 |
| Chuman Limited | Information & communication | 2026 |
| Chums Childcare Limited | Education | 2001 |
| Chunky Frog Design Limited | Information & communication | 2009 |
| Church Construction Limited | Construction | 2018 |
| Church Green Management (Roxwell) Limited | Households | 1968 |
| Church Pastures Management Company Limited | Households | 2018 |
| Church Road Boreham Management Limited | Households | 2004 |
| Churches Visitor and Tourism Association | Education | 2002 |
| Churchill Plumbing and Heating Ltd | Construction | 2023 |
| Chuximms Logistics Ltd | Administrative & support | 2025 |
| CHX Services Limited | Administrative & support | 2018 |
| Chyandour Holdings Limited | Real estate | 2017 |
| Chyandour Limited | Real estate | 2016 |
| Ciab Ltd | Transport & logistics | 2019 |
| Cicet Academy Limited | Education | 2024 |
| CIE Living Ltd | Real estate | 2024 |
| CIE Residential Ltd | Real estate | 2024 |
| Ciemadeit Media Ltd | Information & communication | 2023 |
| CIG Insurance Services Limited | Administrative & support | 1999 |
| Cinch Connectivity Solutions Limited | Manufacturing | 1986 |
| Cinked Ltd | Information & communication | 2017 |
| Circle Roofing Limited | Construction | 2020 |
| Circleconnect Technologies Limited | Information & communication | 2012 |
| Circuit Graphics Limited | Other services | 1995 |
| Cirro Building Services Ltd | Construction | 2014 |
| CIS Self Employed Limited | Extraterritorial | 2013 |
| Citadel Security MGA Limited | Information & communication | 2025 |
| Citadel Security Technology Limited | Information & communication | 2025 |
| City Bowl Limited | Arts & recreation | 2023 |
| City Build Developments Limited | Construction | 2015 |
| City Fencing Limited | Administrative & support | 2025 |
| City Hire London Limited | Administrative & support | 2022 |
| City Lighting Services Limited | Manufacturing | 2012 |
| City Salon Group Limited | Other services | 2025 |
| City Vehicle Rentals Ltd | Wholesale & retail | 2018 |
| City Ventilation (London) Ltd | Construction | 2011 |
| City Water Pre-Com Limited | Water & waste | 2008 |
| Citygate Computers Limited | Manufacturing | 1998 |
| Cityscape Consultancy Ltd | Professional & scientific | 2022 |
| Cityview Consult Ltd | Real estate | 2024 |
| Citywater Services Ltd | Water & waste | 2021 |
| CJ Mac’S Ltd | Hospitality | 2024 |
| CJ Smith Developments Ltd | Construction | 2023 |
| CJH Holdings Limited | Financial services | 2003 |
| CJH Training Limited | Education | 2023 |
| CJM Asbestos Services Ltd | Construction | 2020 |
| CJN Cleaning Services Ltd | Administrative & support | 2018 |
| CJP Publicity Ltd | Professional & scientific | 2025 |
| Cjplaud Limited | Administrative & support | 2022 |
| CJW Interiors & Property Maintenance (Essex) Limited | Construction | 2011 |
| CJW Plumbing & Heating Limited | Construction | 2011 |
| CL Electrical and Security Services Limited | Construction | 2019 |
| Claire Chattey Limited | Administrative & support | 2017 |
| Claire Gilbert Ltd | Arts & recreation | 2020 |
| Claire Grigg Ltd | Health & social care | 2025 |
| Claire Rich Limited | Health & social care | 2012 |
| Claire W 1:1 Ltd | Wholesale & retail | 2021 |
| Clappersgate Limited | Manufacturing | 2021 |
| Clapro Limited | Wholesale & retail | 1959 |
| Clare in the Community Ltd | Health & social care | 2025 |
| Clare Ivor Consulting Ltd | Professional & scientific | 2024 |
| Clarendon Equine Clinic Limited | Professional & scientific | 2018 |
| Clarity SEN Consultancy Limited | Education | 2018 |
| Clarity Wills Limited | Professional & scientific | 2025 |
| Clark & Kent UK Ltd | Professional & scientific | 2010 |
| Clarke Building Limited | Construction | 2015 |
| Class (UK) Limited | Health & social care | 2012 |
| Class Management Holdings Limited | Financial services | 2020 |
| Class One Computer Systems Limited | Information & communication | 1995 |
| Class Productions Finishes Limited | Construction | 2011 |
| Classic Fresh Foods Limited | Wholesale & retail | 1997 |
| Classy Gifts Ltd | Wholesale & retail | 2019 |
| Clavering Investments Ltd | Agriculture & fishing | 2025 |
| Clay Designs Ltd | Professional & scientific | 2011 |