| Chris Cleal Rail Limited | Construction | 2011 |
| Chris Curd Design Limited | Information & communication | 2007 |
| Chris Housego Limited | Arts & recreation | 2025 |
| Chris Premier Travel Ltd | Transport & logistics | 2026 |
| Chrispod UK Limited | Hospitality | 2017 |
| Christ Family Foursquare Church | Other services | 2020 |
| Christ the Redeemer College | Education | 2005 |
| Christchurch Freehold Property Limited | Households | 2019 |
| Christensen Holdings Limited | Real estate | 2023 |
| Christer's Gold Limited | Wholesale & retail | 2022 |
| Christers Futures Ltd | Real estate | 2011 |
| Christian Brensing Enterprises Limited | Professional & scientific | 2012 |
| Christina Jordan Limited | Wholesale & retail | 2021 |
| Christmas House Corporations and Holdings Ltd | Financial services | 2013 |
| Christmas Karma Limited | Information & communication | 2023 |
| Christopher Bentley Limited | Real estate | 2026 |
| Christopher Rawlinson & Company Limited | Real estate | 2008 |
| Christopher Romaniuk Limited | Health & social care | 2015 |
| Christophorus International Limited | Extraterritorial | 1980 |
| Christos Jewellery Limited | Wholesale & retail | 2016 |
| Christosm Limited | Wholesale & retail | 2011 |
| Christy Fallon Carpentry Services Limited | Construction | 2014 |
| Chromacraft Limited | Wholesale & retail | 2024 |
| Chrome Artificial Jewellery Limited | Manufacturing | 2017 |
| Chromefields Limited | Information & communication | 2012 |
| Chron Productions Ltd | Information & communication | 2021 |
| Chronwell Collective Ltd | Wholesale & retail | 2025 |
| Chrysolite Limited | Real estate | 2009 |
| Chuckwalla Touring Ltd | Arts & recreation | 2020 |
| Chudasama Property Investment LLP | | 2018 |
| Chui Solutions Limited | Administrative & support | 2021 |
| Chulo Consulting Limited | Professional & scientific | 2025 |
| Chulo Squad Ltd | Hospitality | 2025 |
| Chung DAM Limited | Administrative & support | 2022 |
| Chunky’S Detailing Ltd | Wholesale & retail | 2020 |
| Chupa Limited | Wholesale & retail | 2026 |
| Church Farm Glocs Ltd | Real estate | 2023 |
| Churchfields Residents Association (Harrow) Limited | Households | 1993 |
| Churchill and Hopkins Production Limited | Information & communication | 2022 |
| Churchill Court (Nugents Park) Limited | Households | 2021 |
| Churchill Property Consultants Limited | Real estate | 2020 |
| Churchlane Property Development Limited | Real estate | 2019 |
| Churton Property Developments Limited | Real estate | 1994 |
| Ciaran Walsh Limited | Health & social care | 2011 |
| Cibus Biotechnologies UK Ltd | Professional & scientific | 2025 |
| Cicscape Consulting Limited | Information & communication | 2013 |
| Cideas Ltd | Wholesale & retail | 2017 |
| Cidem Brickwork Ltd | Construction | 2020 |
| Cidon Limited | Professional & scientific | 2011 |
| Ciencia Health Limited | Health & social care | 2019 |
| Ciencia Wellbeing Limited | Health & social care | 2022 |
| Cignella Wellness Limited | Hospitality | 2015 |
| Cigniti Technologies (UK) Limited | Information & communication | 2014 |
| CIL (ABU Dhabi) Limited | Professional & scientific | 2005 |
| Cilica Construction Ltd | Construction | 2019 |
| Cimex Pest Control Ltd | Health & social care | 2015 |
| Cims Investments Ltd | Real estate | 2024 |
| Cinar Supply Ltd | Wholesale & retail | 2024 |
| Cindy Property Service Ltd | Real estate | 2025 |
| Cinematic Blondes Collective Ltd | Information & communication | 2024 |
| Cinephilia Services Limited | Information & communication | 1999 |
| Cinetiks Music Ltd | Information & communication | 2018 |
| Cinetime Ltd | Information & communication | 2018 |
| Cini Cloud Private Ltd | Information & communication | 2018 |
| Cinnamon Green Ltd | Hospitality | 2023 |
| Cinnamon Restaurant Limited | Hospitality | 2008 |
| Cintamani Consulting Limited | Information & communication | 2025 |
| Cioby Facilities Ltd | Construction | 2017 |
| Ciorcea GEO Ltd | Construction | 2015 |
| CIP Interiors Limited | Construction | 2015 |
| CIP Plastering & Decorating Ltd | Construction | 2023 |
| Cipriana Pinnacle Limited | Construction | 2026 |
| Cipriana Northwood Limited | Construction | 2025 |
| Circle Facades Limited | Construction | 2020 |
| Circle Vista Ltd | Professional & scientific | 2024 |
| CIRCLE2 Ltd | Information & communication | 2023 |
| Circuit Couriers Ltd | Transport & logistics | 2020 |
| Cirro Lite (Europe) Limited | Wholesale & retail | 1992 |
| Cirrus Containments Holdings Limited | Professional & scientific | 2025 |
| Cirrus Containments Limited | Professional & scientific | 2013 |
| CIS Club Ltd | Extraterritorial | 2009 |
| Cisko Limited | Wholesale & retail | 2010 |
| Cistus Freight Services Ltd | Transport & logistics | 2021 |
| Citadal Limited | Wholesale & retail | 2024 |
| Citadel Communication Strategies Ltd | Professional & scientific | 2025 |
| CITADEL9 Ltd | Professional & scientific | 2018 |
| Citi LUX Ltd | Wholesale & retail | 2019 |
| Citi Nests Charing Limited | Real estate | 2018 |
| Citi Property Marketing Limited | Real estate | 2019 |
| Citi Trading Limited | Extraterritorial | 2012 |
| Citi Venture Group Ltd | Financial services | 2017 |
| Citiguard Security (UK) Ltd | Administrative & support | 2013 |
| Citrine Ltd | Construction | 2023 |
| Citrine Towers Limited | Financial services | 2023 |
| City & Borough Estates Ltd | Construction | 2022 |
| City Air Limited | Construction | 2004 |
| City Building and Roofing Ltd | Construction | 2018 |
| City Centre Homes UK Ltd | Real estate | 2024 |
| City Clean Holdings Ltd | Professional & scientific | 2026 |
| City Clean SERVICE1 Ltd | Professional & scientific | 2026 |