| Celentiq Ltd | Information & communication | 2025 |
| Ceneden Renewables Ltd | Professional & scientific | 2022 |
| Central Horse Retirement Ltd | Administrative & support | 2004 |
| Central Tyre (Commercial) Limited | Wholesale & retail | 2011 |
| Century 21 Investments Ltd | Real estate | 2018 |
| Cfis Properties Limited | Real estate | 2023 |
| Cfpw Limited | Agriculture & fishing | 2003 |
| CG Fundraising Consultancy Limited | Professional & scientific | 2013 |
| CGC Analytics Limited | Information & communication | 2013 |
| CGS Precision Medicine Consultancy Limited | Health & social care | 2020 |
| CH ROE Limited | Real estate | 2021 |
| Chacha Shoker Ltd | Real estate | 2022 |
| Chalfont Building Services Limited | Construction | 2007 |
| Challenge Property Limited | Real estate | 2025 |
| Challens Developments Limited | Financial services | 2023 |
| Chambers Brothers Ltd | Real estate | 2021 |
| Chambers IP Ltd | Professional & scientific | 2024 |
| Chandarana Retail Group Ltd | Wholesale & retail | 2025 |
| Chapmans Yard RTM Company Limited | Households | 2014 |
| Charchem Ltd | Education | 2018 |
| Charis Social Care Ltd | Health & social care | 2018 |
| Charles Court Management Company (Letchworth) Limited | Households | 1988 |
| Charleswater Europe Limited | Professional & scientific | 2001 |
| Charming Place (Clifton) Management Company Limited | Real estate | 2026 |
| Charmon London Limited | Real estate | 1975 |
| Charter UK Properties Ltd | Real estate | 2009 |
| Chasestead Group Limited | Manufacturing | 2012 |
| Chasestead Holdings Limited | Financial services | 2019 |
| Chasestead LV Limited | Manufacturing | 2016 |
| Chasestead Special Projects LLP | | 2012 |
| Chaspurs Limited | Hospitality | 2002 |
| Chelsea and Callum UK Ltd | Wholesale & retail | 2024 |
| Chestnut Walk (Hitchin) Residents Company Limited | Real estate | 1993 |
| Chicken & Pizza Lounge Limited | Hospitality | 2022 |
| Chilfen Contracting Limited | Construction | 2010 |
| Chilfen Export Packaging Limited | Manufacturing | 2010 |
| Chilfen Joinery Limited | Manufacturing | 1985 |
| Choppieworld Limited | Professional & scientific | 2012 |
| Chris Mence Production Lighting Limited | Arts & recreation | 2014 |
| Christie Building Services Limited | Real estate | 2020 |
| Chun CHA Limited | Hospitality | 2022 |
| Church Farm Assembly Limited | Manufacturing | 2014 |
| Church Lane Mews Limited | Real estate | 2023 |
| Churro Boyz Limited | Hospitality | 2021 |
| Cinescreen AV Limited | Administrative & support | 2004 |
| Cipher Energetics Limited | Health & social care | 2026 |
| Circellus Ltd | Professional & scientific | 2024 |
| CIRCUIT-1 Ltd | Construction | 2014 |
| CJ Associates (Accounts & Tax) Limited | Professional & scientific | 2008 |
| CJA Designs Limited | Information & communication | 2018 |
| CJC Real Estate Limited | Real estate | 2017 |
| CK Consultants Ltd | Extraterritorial | 2020 |
| CKB Ltd | Wholesale & retail | 2010 |
| CKR Consultants Limited | Administrative & support | 2014 |
| Clan Letting Ltd | Real estate | 2021 |
| Clancy Cloud Consulting Limited | Information & communication | 2017 |
| Clarcam Properties Ltd | Real estate | 2021 |
| Clarks Garage (Walkern) Limited | Wholesale & retail | 1981 |
| Classic Creative Home Improvements Limited | Construction | 1996 |
| Claymore Asset Management Limited | Real estate | 2009 |
| Claymore Estates Limited | Real estate | 2015 |
| Claymore Group LLP | | 2008 |
| Claymore Investment Managers Ltd | Real estate | 2018 |
| Claymore Phoenix (Knoll) Limited | Real estate | 2019 |
| Claymore Phoenix Limited | Real estate | 2009 |
| Clean 4 U Cleaning Ltd | Administrative & support | 2025 |
| Clearline Trading Limited | Wholesale & retail | 2017 |
| CLH Property Holdings Limited | Real estate | 2025 |
| Cliff Kaneli Ltd | Other services | 2016 |
| Clinic 6 Ltd | Health & social care | 2022 |
| Cloisters Event Limited | Other services | 2019 |
| Close Encounters Limited | Wholesale & retail | 2004 |
| Clothall Corner Estate Management Limited | Households | 2011 |
| Clothall Corner Flat Management Limited | Households | 2011 |
| Cloud Chameleons Limited | Information & communication | 2017 |
| Cloud Rock Stars Ltd | Information & communication | 2018 |
| CM Adventure UK Ltd | Arts & recreation | 2019 |
| CM Tenger (London) Limited | Real estate | 2020 |
| CMS Ventilation Ltd | Construction | 2026 |
| Coach Write Speak Ltd | Professional & scientific | 2023 |
| Coaching With Adam Limited | Other services | 2023 |
| Coda Music UK Limited | Wholesale & retail | 2000 |
| Coda Music UK Trustees Limited | Administrative & support | 2022 |
| Coffee House Group Limited | Financial services | 2021 |
| Coffeeing the World UK Ltd | Wholesale & retail | 2023 |
| Cogniora Consulting Ltd | Professional & scientific | 2025 |
| Coil Slitting Holdings Limited | Financial services | 2023 |
| Coil Slitting Letchworth Limited | Other services | 1993 |
| Colbys Logistic Solutions Ltd | Wholesale & retail | 2025 |
| Collida Limited | Construction | 2001 |
| Colocation Ltd | Information & communication | 2023 |
| Coloured Bricks Ltd | Real estate | 2021 |
| Comeuphigher Togreaterlevels Community Club CIC | Professional & scientific | 2024 |
| Commercial Choice Clearances Ltd | Transport & logistics | 2025 |
| Commercial Real Estate Advisory Ltd | Professional & scientific | 2014 |
| Commercial Shopfitters Ltd | Construction | 2014 |
| Commsglobal Ltd | Information & communication | 2022 |
| Compact Audio Limited | Wholesale & retail | 2012 |
| Companion Animals and Equine (Responsible Medicine USE) Limited | Other services | 2021 |
| Compassion Plus Health Care Limited | Health & social care | 2014 |