| Coriant Group Limited | Financial services | 2024 |
| Cork Tree Estates LLP | | 2010 |
| Cornall Performance Coaching Ltd | Administrative & support | 2023 |
| Cornerstone & Co Property Ltd | Real estate | 2026 |
| Cornwallis Business Centre Limited | Real estate | 1987 |
| Coro Fire Protection Ltd | Construction | 2019 |
| Corporate Intelligence Group Limited | Professional & scientific | 2019 |
| Corporate Property Rentals Ltd | Real estate | 2024 |
| Corringham Building Services Limited | Construction | 2025 |
| Corringham Bull (PH) Ltd | Hospitality | 2010 |
| Cosmin & Daria Trans Ltd | Transport & logistics | 2019 |
| Cosmos - Bentalls Limited | Hospitality | 2016 |
| Cosmos Airforce Ltd | Extraterritorial | 2021 |
| Cosmos Catering Ltd | Wholesale & retail | 2016 |
| Cosmos Eastwood Ltd | Hospitality | 2013 |
| Costello PUB Co Ltd | Hospitality | 2025 |
| Costello PUB Group Ltd | Hospitality | 2026 |
| Costema Property Services Limited | Real estate | 2018 |
| Costy and DYA Limited | Construction | 2025 |
| Cottage Catering Hire Limited | Hospitality | 2020 |
| Coules LDN Limited | Other services | 2019 |
| Counterfire Limited | Manufacturing | 2003 |
| Country Fayre Catering Ltd | Hospitality | 2023 |
| County Decorating Contractors Limited | Construction | 2000 |
| County Groundbaits Limited | Wholesale & retail | 2006 |
| Countywide Fencing Limited | Construction | 2025 |
| Court Hill Limited | Health & social care | 2013 |
| Courtenay Compliance Limited | Administrative & support | 2019 |
| Courtney Coker Tattoos Limited | Other services | 2024 |
| Courtney Consultancy Limited | Professional & scientific | 2013 |
| Coverdale Specialist Contracting Limited | Construction | 2008 |
| Covert Angling Ltd | Agriculture & fishing | 2025 |
| Covidiu Transport Limited | Transport & logistics | 2023 |
| Cowling Consulting Limited | Professional & scientific | 2001 |
| CP Scaffolding Solutions Ltd | Construction | 2017 |
| Cp&R Management Limited | Construction | 2024 |
| CPA Construction Ltd | Construction | 2023 |
| CPM24 Ltd | Real estate | 1998 |
| CPN Health and Safety Consultancy Limited | Professional & scientific | 2021 |
| CPS Engineering Employees' Trustee Limited | Administrative & support | 2024 |
| CPS Engineering Limited | Manufacturing | 2002 |
| CPW Flooring Limited | Construction | 2022 |
| CPW Resourcing Ltd | Administrative & support | 2011 |
| CR Crossfit Ltd | Education | 2022 |
| Craft Axis Ltd | Wholesale & retail | 2025 |
| Craftman Maintenance Ltd | Construction | 2017 |
| Craftsandbusygifts Ltd | Wholesale & retail | 2021 |
| Craig Tokley Real Estate Ltd | Real estate | 2026 |
| Cranes Close (Basildon) Management Company Limited | Real estate | 2020 |
| Cranstonmiller Limited | Professional & scientific | 2013 |
| Crawford Manchester Design Ltd | Professional & scientific | 2024 |
| Crawford Temple Limited | Professional & scientific | 2002 |
| Crawfords Contract Services Limited | Administrative & support | 2022 |
| Crayford Sybourn Limited | Transport & logistics | 2004 |
| CRD Cleaning Ltd | Wholesale & retail | 2020 |
| Crdi Ltd | Wholesale & retail | 2025 |
| Cream Ideas Limited | Administrative & support | 2015 |
| Creata Tech Solutions Ltd | Wholesale & retail | 2016 |
| Creative Dream Designs Ltd | Other services | 2020 |
| Creative FIX Solutions Ltd | Construction | 2017 |
| Creative Outpost Limited | Information & communication | 2014 |
| Creative Team Limited | Professional & scientific | 2014 |
| Creator Stream Ltd | Administrative & support | 2023 |
| Creaven Consulting Limited | Administrative & support | 2025 |
| Credence Alert Ltd | Professional & scientific | 2026 |
| Creekview EMS Limited | Manufacturing | 2020 |
| Crepe Atelier Ltd | Hospitality | 2025 |
| Crescent Homes Holdings Ltd | Real estate | 2020 |
| Cresco Multi Academy Trust | Education | 2011 |
| CRG Fire Protection Ltd | Extraterritorial | 2023 |
| CRH Flooring Ltd | Construction | 2023 |
| Cris Jarvis Design Limited | Construction | 2015 |
| Criss Transport Ltd | Transport & logistics | 2025 |
| Crissr Ltd | Manufacturing | 2025 |
| Critical AI Ltd | Information & communication | 2025 |
| CRM Refurbishment Ltd | Construction | 2023 |
| CRM Scaffolding Limited | Construction | 2025 |
| Crma Services Ltd | Transport & logistics | 2025 |
| Crocus Wealth Limited | Financial services | 1999 |
| Croitoru Trans Ltd | Transport & logistics | 2016 |
| Cross-Ocean Transactions Limited | Wholesale & retail | 2024 |
| Crown Construction of Essex Limited | Construction | 2021 |
| Crown of Beauty Meditation Practice Ltd | Wholesale & retail | 2022 |
| Crown Sentinel Services Ltd | Administrative & support | 2025 |
| Crownlight Healthcare Ltd | Health & social care | 2024 |
| Crusaders Security Ltd | Construction | 2022 |
| Cruxsol Limited | Information & communication | 2018 |
| Crystal & Clear Cleaning Limited | Administrative & support | 2017 |
| Crystal Clear Optix Ltd | Wholesale & retail | 2023 |
| Crystalclear Spas Ltd | Wholesale & retail | 2019 |
| Crystalgold Fabrics and Designs Limited | Wholesale & retail | 2024 |
| Crystals & Tea Limited | Wholesale & retail | 2022 |
| CS GAS & Mechanical Services Ltd | Other services | 2023 |
| CS Technical Staffing Limited | Administrative & support | 2024 |
| Csara Holdings Limited | Wholesale & retail | 2023 |
| CSB Customs Limited | Professional & scientific | 2019 |
| CSC Plumbing Solutions Ltd | Construction | 2024 |
| Cscp UK Ltd | Health & social care | 2026 |
| Csiempress Ltd | Manufacturing | 2017 |
| Cskh Limited | Professional & scientific | 2011 |