| Clean Air Environmental Limited | Professional & scientific | 2017 |
| Clean ANY Home Ltd | Administrative & support | 2021 |
| Clean GAS Technologies Ltd | Water & waste | 2012 |
| Clear Wealth Planning Ltd | Financial services | 2016 |
| Clearbow Limited | Administrative & support | 2021 |
| Clearwood Property Limited | Real estate | 2023 |
| Cleaver Cook Consultancy Limited | Professional & scientific | 2007 |
| Cleaver Cook LLP | | 2006 |
| Clee Hill Investments Limited | Other services | 2017 |
| Cleethorpes Property and Finance Company Limited | Real estate | 1952 |
| Clegg Humphreys Limited | Extraterritorial | 1975 |
| Clenn Engineering Limited | Manufacturing | 2013 |
| Clevedon Fasteners Limited | Manufacturing | 1999 |
| Clevedon Holdings Limited | Financial services | 2025 |
| Cleverlyn Limited | Professional & scientific | 1985 |
| Clevtec Limited | Wholesale & retail | 2010 |
| CLF Mechanical Ltd | Construction | 2019 |
| Click Developments Limited | Professional & scientific | 2013 |
| Clifton Textiles Limited | Wholesale & retail | 1998 |
| Clinecho Ltd | Information & communication | 2026 |
| Clinical Independent Prescribing Solutions Limited | Health & social care | 2025 |
| Clinical Therapy Group Ltd | Health & social care | 2015 |
| Clinton Ecurie LLP | | 2012 |
| CLJ Distributions Ltd | Wholesale & retail | 2025 |
| Cloak Vintage Limited | Wholesale & retail | 2023 |
| Clock Chambers Ltd | Professional & scientific | 2013 |
| Cloud Music Ltd | Information & communication | 2012 |
| Cloud Zion Limited | Information & communication | 2008 |
| Clouds Childrens Care Limited | Health & social care | 2014 |
| Clover Accountants Ltd | Professional & scientific | 2013 |
| CLR Hagan Properties Ltd | Real estate | 2026 |
| CLR Solutions Ltd | Information & communication | 2013 |
| Cluego Ltd | Arts & recreation | 2014 |
| Cluton Propco 1 (Digbeth) Limited | Real estate | 2019 |
| Cluton Propco Holdings Limited | Real estate | 2019 |
| Cmart Ltd | Transport & logistics | 2015 |
| CMK Kitchen and Ventilation Specialists Limited | Administrative & support | 2017 |
| CN Art Ltd | Arts & recreation | 2016 |
| CNA Automotive Recruitment Limited | Administrative & support | 2012 |
| CNW Drive UK Ltd | Wholesale & retail | 2020 |
| CNW Properties Ltd | Real estate | 2018 |
| Coairy Ltd | Transport & logistics | 2021 |
| Cobbold & Co Limited | Professional & scientific | 2013 |
| Cobham Homes Limited | Real estate | 2020 |
| Cobre Consultants Limited | Professional & scientific | 2001 |
| Coburg Banks IT Contracting Ltd | Administrative & support | 2020 |
| Coburg Banks IT Ltd | Administrative & support | 2006 |
| Cockburn Property Holdings Limited | Real estate | 2023 |
| Cockerell & Young's Ltd | Administrative & support | 2025 |
| Cockerell Tree Care LLP | | 2025 |
| Cocktail Facials Limited | Health & social care | 2020 |
| Coda Building Consultancy Limited | Administrative & support | 2014 |
| Codeflex Consultants Ltd | Information & communication | 2024 |
| Codifi Ltd | Information & communication | 2017 |
| Codsall News Express Ltd | Wholesale & retail | 2023 |
| COE Scaffolding Services Ltd | Construction | 2019 |
| Coffee & Caviar Ltd | Wholesale & retail | 2025 |
| Cogent Insight Limited | Education | 2019 |
| Cognitive Edge AI Ltd | Information & communication | 2025 |
| Colbeh Catering Limited | Hospitality | 2016 |
| Colden Human Resources Limited | Professional & scientific | 2009 |
| Coldfield Capital Ltd | Real estate | 2026 |
| Coldfield Construction Limited | Construction | 2022 |
| Cole Creative Communications Limited | Professional & scientific | 2000 |
| Coleshill Building Materials Ltd | Water & waste | 2025 |
| Coley Civil Engineering Services Limited | Professional & scientific | 2022 |
| Colhar Medical Limited | Extraterritorial | 2015 |
| Colin J.B. Spinks & Co. Ltd | Professional & scientific | 2009 |
| Collection (WSM) & Co Limited | Wholesale & retail | 2015 |
| Colmore Investment Group Limited | Professional & scientific | 2021 |
| Colonic Health by Sarah C Ltd | Health & social care | 2025 |
| Colorectal Solutions Ltd | Health & social care | 2019 |
| Colour & Beauty Limited | Other services | 2013 |
| Colton Property Limited | Real estate | 2024 |
| Colton Residential Limited | Households | 2024 |
| Combat Commissioning Services Limited | Manufacturing | 2011 |
| Combine Healthcare Services Limited | Health & social care | 2019 |
| Comest Ltd | Information & communication | 2026 |
| Comfort Beds Furniture Bros Co Limited | Wholesale & retail | 2008 |
| Comfort Midland Properties Ltd | Real estate | 2025 |
| Commander Partnership Limited | Extraterritorial | 2006 |
| Commercial Catering Products Limited | Hospitality | 2020 |
| Commercial Design Consultancy Ltd | Professional & scientific | 2023 |
| Commercial Gates Limited | Wholesale & retail | 2022 |
| Commercial TL Ltd | Manufacturing | 2021 |
| Commercial Vehicle Procurement Ltd | Wholesale & retail | 2012 |
| Commexpo Ltd | Wholesale & retail | 2010 |
| Commiphora Ltd | Hospitality | 2022 |
| Community Bliss CIC | Administrative & support | 2026 |
| Community Care Assist Ltd | Administrative & support | 2009 |
| Compact Cloud Ltd | Information & communication | 2022 |
| Compactor Solutions Limited | Wholesale & retail | 2012 |
| Compas Direct Services Limited | Information & communication | 2009 |
| Complete Accounts Solutions Ltd | Professional & scientific | 2006 |
| Complete Community Care Midlands Limited | Health & social care | 2011 |
| Complete Fire and Security Ltd | Administrative & support | 2014 |
| Complete Medicare Limited | Health & social care | 2017 |
| Completely Plastered Ltd | Construction | 2026 |
| Completely Satisfied Limited | Wholesale & retail | 2010 |
| Compliance for Schools Ltd | Professional & scientific | 2019 |