| Clarendon Road Property 1 Ltd | Real estate | 2026 |
| Clarendon Road Property 2 Ltd | Real estate | 2026 |
| Clarity Beauty Solutions Limited | Other services | 2016 |
| Clarity Designs (UK) Limited | Wholesale & retail | 2013 |
| Clarity Entertainment Limited | Arts & recreation | 2017 |
| Claritycrest Consulting Ltd | Information & communication | 2023 |
| Clark Property Improvements Limited | Construction | 2019 |
| Clark Solutions Limited | Professional & scientific | 2011 |
| Clarke and Phillips Properties Ltd | Real estate | 2021 |
| Clarke Learning Consultancy Ltd | Administrative & support | 2017 |
| Clarke Thorne Properties Ltd | Real estate | 2024 |
| Classic B Club Limited | Wholesale & retail | 2026 |
| Classic Cars Direct Ltd | Wholesale & retail | 2018 |
| Classic Kits Ltd | Wholesale & retail | 2015 |
| Classic Loft Conversions Limited | Construction | 2013 |
| Classic Services Group (CSG) Ltd | Administrative & support | 2023 |
| Classy Build Ltd | Real estate | 2025 |
| Classy Driveways Ltd | Construction | 2014 |
| Clause Law Ltd | Information & communication | 2025 |
| Claves Estates Limited | Real estate | 2020 |
| Clawbrace Ltd | Wholesale & retail | 2018 |
| Clay and Jewel Ltd | Manufacturing | 2021 |
| Clay and More Limited | Wholesale & retail | 2026 |
| Clayden Consultancy Services Limited | Administrative & support | 2025 |
| Claystation Ltd | Arts & recreation | 2023 |
| Clayton Components Limited | Wholesale & retail | 2021 |
| Clayton Project Solutions Limited | Administrative & support | 2012 |
| CLC Business Solutions Ltd | Administrative & support | 2026 |
| CLC Development Ltd | Information & communication | 2015 |
| Clckd Media Limited | Administrative & support | 2025 |
| CLD Nutrition Ltd | Health & social care | 2023 |
| CLD Signalling Limited | Administrative & support | 2017 |
| Clean & Green Gardens Ltd | Administrative & support | 2019 |
| Clean 2 Day Ltd | Administrative & support | 2025 |
| Clean Air Control Limited | Construction | 2023 |
| Clean Air Limited | Manufacturing | 1994 |
| Clean Airflow Ltd | Construction | 2026 |
| Clean BYE Ltd | Administrative & support | 2025 |
| Clean Dispatch Limited | Other services | 2019 |
| Clean My Waste Ltd | Water & waste | 2024 |
| Clean Planet Northwest Ltd | Water & waste | 2024 |
| Clean Protect & Revive Ltd | Other services | 2025 |
| Clean Street Bolton Limited | Other services | 2025 |
| Clean Sweep Northwest Limited | Administrative & support | 2025 |
| Cleaner Gardens Limited | Administrative & support | 2018 |
| Cleanfabrics Ltd | Other services | 2019 |
| Cleanify Solutions Ltd | Administrative & support | 2024 |
| Cleaning League UK Ltd | Administrative & support | 2025 |
| Cleaningbundles Ltd | Wholesale & retail | 2024 |
| Cleaningmaster (NW) Ltd | Administrative & support | 2019 |
| Clear Clean Services Limited | Administrative & support | 2019 |
| Clear Clinics Limited | Health & social care | 2020 |
| Clear Comparison Limited | Construction | 2020 |
| Clear Directions Ltd | Health & social care | 2025 |
| Clear Double Glazing Ltd | Construction | 2026 |
| Clear Engagement Limited | Administrative & support | 2021 |
| Clear Fonts Graphics Ltd | Manufacturing | 2024 |
| Clear Logic Money Ltd | Financial services | 2018 |
| Clear Marketing Acquisitions Limited | Professional & scientific | 2012 |
| Clear Marketing Communications Limited | Professional & scientific | 1996 |
| Clear UP Ltd | Administrative & support | 2026 |
| Clear Vibrations Ltd | Information & communication | 2019 |
| Clear Vision 34 Holdings Limited | Financial services | 2023 |
| Clear Vision 34 Ltd | Professional & scientific | 2020 |
| Clear Vision Group Ltd | Real estate | 2021 |
| Clear Vision Wealth Management Ltd | Financial services | 2021 |
| Cleartech Communications Ltd | Information & communication | 2019 |
| Cleartech Estates Ltd | Real estate | 2023 |
| Cleartech Systems Ltd | Information & communication | 2020 |
| Clearwater Risk Management Limited | Professional & scientific | 2001 |
| Clearwater Village Management (2) Limited | Households | 2003 |
| Cleddau Country Escapes Ltd | Extraterritorial | 2021 |
| Cleddau Group Ltd | Financial services | 2018 |
| Cleddau Property Management Ltd | Real estate | 2021 |
| Clemson Technologies Ltd | Manufacturing | 2024 |
| Cleopatra Catering Ltd | Hospitality | 2020 |
| Clermont Limited | Construction | 2026 |
| Clevelands Prep School Limited | Education | 2015 |
| Clevelands Preparatory School Limited | Education | 1979 |
| Clever Cart Ltd | Wholesale & retail | 2024 |
| Clever Choice Ltd | Construction | 2017 |
| Clever Clause Limited | Professional & scientific | 2013 |
| Clever Talk Ltd | Information & communication | 2015 |
| Click & Discover Ltd | Wholesale & retail | 2024 |
| Click Haul Ltd | Transport & logistics | 2023 |
| Click Witted Ltd | Information & communication | 2022 |
| Clickd Consultancy Ltd | Professional & scientific | 2021 |
| Clicknestic Limited | Wholesale & retail | 2025 |
| Clicks Shift Ltd | Wholesale & retail | 2025 |
| Clidebrower Ltd | Wholesale & retail | 2018 |
| Client's First Financial Consultants Ltd | Financial services | 2016 |
| Clifftech Ltd | Professional & scientific | 2026 |
| Clifton Farm Ltd | Agriculture & fishing | 2025 |
| Clifton Investco Limited | Financial services | 2025 |
| Clifton Trade Bathrooms Limited | Administrative & support | 2005 |
| Climate Control Solutions Ltd | Construction | 2025 |
| Climate Framework Ltd | Professional & scientific | 2023 |
| Climate Glazing Limited | Construction | 2026 |
| Climate Improvements Ltd | Construction | 2020 |
| Climate Law Ltd | Professional & scientific | 2020 |