| Choices Coaching Ltd | Professional & scientific | 2012 |
| Choir Consulting Ltd | Information & communication | 2017 |
| Chok DEE (South) Limited | Wholesale & retail | 2021 |
| Cholso Limited | Construction | 1994 |
| Chop Chop Kitchenware Limited | Wholesale & retail | 2013 |
| Chris Jordan Ltd | Financial services | 2024 |
| Chris Page Productions Ltd | Information & communication | 2021 |
| Chrism Education Limited | Education | 2010 |
| Christian Consultants Limited | Information & communication | 1989 |
| Christie Daniels Limited | Real estate | 2024 |
| Christopher James Architecture Ltd | Professional & scientific | 2026 |
| Christopher Plumbing Services Limited | Construction | 2009 |
| Church Meadows Management Company Limited | Administrative & support | 1989 |
| Church Wickham Limited | Real estate | 2015 |
| CI Lychpit Restaurant Limited | Hospitality | 2020 |
| Cibotrans Ltd | Water & waste | 2024 |
| Cicada Partnership Limited | Administrative & support | 2010 |
| CID Software Ltd | Information & communication | 2006 |
| Cider Money Ltd | Information & communication | 2025 |
| CIG Collections Ltd | Transport & logistics | 2026 |
| Cimteq Holdings Limited | Information & communication | 2018 |
| Cimteq Limited | Information & communication | 1998 |
| Cinetra Trading Limited | Professional & scientific | 2008 |
| Cingulate Ltd | Health & social care | 2019 |
| Cislo Solutions Ltd | Information & communication | 2015 |
| Citadel Management Consulting Limited | Professional & scientific | 2017 |
| City Dental LAB Limited | Manufacturing | 2016 |
| Civital Direct Catering Ltd | Wholesale & retail | 2019 |
| CJC Systems LLP | | 2008 |
| CJK Medical Services Ltd | Health & social care | 2014 |
| Cjssoft Limited | Information & communication | 2008 |
| CK& IA Ltd | Real estate | 2024 |
| CLA Services Ltd | Administrative & support | 2013 |
| Claas Financial Services Limited | Financial services | 2006 |
| Claimstrak Ltd | Information & communication | 2022 |
| Claimstrak Technology Solutions Ltd | Professional & scientific | 2024 |
| Clairvoyant Cloud Limited | Professional & scientific | 2025 |
| Clarel Consulting Limited | Professional & scientific | 2012 |
| Claret and Blue Solutions Limited | Financial services | 2009 |
| Clarion Consulting Limited | Information & communication | 2016 |
| Clarity CFO Ltd | Professional & scientific | 2025 |
| Clarity Personal Design Limited | Other services | 2022 |
| Clark Financial Limited | Financial services | 2002 |
| Clarke & SON LLP | | 2007 |
| Clarke & SON Solicitors Limited | Professional & scientific | 2012 |
| Clarkway Builders Ltd | Construction | 2008 |
| Clarkway Plumbing and Heating Ltd | Construction | 2022 |
| Classic and Prestige Car Storage Limited | Transport & logistics | 2019 |
| Classic Hampshire Ltd | Other services | 2018 |
| Classic Vintage Limited | Wholesale & retail | 2024 |
| Claydon Cheltenham Limited | Health & social care | 2016 |
| Clbv Limited | Administrative & support | 1997 |
| Clean Fresh Limited | Other services | 2017 |
| Clean Business (UK) Limited | Administrative & support | 2010 |
| Cleanbase Cleaning Limited | Administrative & support | 2024 |
| Cleanupkrew Limited | Administrative & support | 2025 |
| Clear Blue Sky Consulting Limited | Information & communication | 2017 |
| Clear H2O Window Cleaning Ltd | Administrative & support | 2022 |
| Clear H2O Window Cleaning Services Limited | Other services | 2012 |
| Clear Path Counselling Ltd | Health & social care | 2022 |
| Clear Signal Communications Ltd. | Professional & scientific | 2005 |
| Clear Space Solutions Group Ltd | Construction | 2025 |
| Clearchoiceatm Limited | Financial services | 2023 |
| Clearstone Consulting Limited | Information & communication | 2010 |
| Cleaves Construction Ltd | Construction | 2021 |
| Clematis Properties Limited | Administrative & support | 2010 |
| Cleresden Land Ltd | Agriculture & fishing | 2012 |
| Clever Construction Ltd | Construction | 2017 |
| Clever Driver Ltd | Transport & logistics | 2017 |
| Click 71 Ltd | Information & communication | 2005 |
| Cliddesden Court Estates Limited | Administrative & support | 2011 |
| Cliddesden Heights Management Company Limited | Households | 2011 |
| Cliffords Blinds Ltd | Wholesale & retail | 2021 |
| Climateworksuk Ltd | Construction | 2023 |
| Clinical Psychology London Ltd | Health & social care | 2022 |
| Clinixir Limited | Extraterritorial | 2014 |
| Clipit Enterprise Ltd | Manufacturing | 2022 |
| Clippin’ Marvellous Dog Grooming Ltd | Extraterritorial | 2023 |
| Clippin’ Marvellous Ltd | Extraterritorial | 2023 |
| Clix Technology Ltd | Wholesale & retail | 2021 |
| Clone Media EOT Limited | Financial services | 2025 |
| Clone Media Technology Limited | Information & communication | 2007 |
| Cloud 10 Property Management Limited | Real estate | 2021 |
| Cloud Blueprints Ltd | Information & communication | 2022 |
| CLOUD87 Ltd | Professional & scientific | 2024 |
| Cloudopsai Limited | Information & communication | 2025 |
| Cloudr Ltd | Information & communication | 2026 |
| Cloudzy Ltd | Information & communication | 2024 |
| Clouvider Limited | Information & communication | 2013 |
| Clover & Thistle Limited | Extraterritorial | 2013 |
| Club Champion Buyco Limited | Financial services | 2022 |
| Clubseller Ltd | Wholesale & retail | 2014 |
| CMC Heating Solutions Ltd | Construction | 2017 |
| CMC Subsea Inspection Ltd | Construction | 2019 |
| CMJ Design Limited | Professional & scientific | 2024 |
| CMK Fashion Limited | Wholesale & retail | 2022 |
| CMM Cargo Ltd | Transport & logistics | 2025 |
| CMR Legal Limited | Professional & scientific | 2025 |
| CMT 2008 Ltd | Transport & logistics | 2022 |
| CNA Delivery Ltd | Transport & logistics | 2025 |