| Chess Roofing Ltd | Construction | 2021 |
| Chester Hotel Operations Ltd | Hospitality | 2025 |
| Chester West Hotels Ltd | Hospitality | 2025 |
| Chestnuts Holdings Limited | Financial services | 2023 |
| Chianche Ltd | Real estate | 2023 |
| Chickywicks Nurseries Limited | Education | 2008 |
| Chiltern Joinery Ltd | Manufacturing | 2023 |
| Chiltern Sauna Ltd | Other services | 2025 |
| Chimeras (UK) Holdings Ltd | Professional & scientific | 2024 |
| Chiswick Green Studios Limited | Households | 1996 |
| Choose Your Own Adventure Limited | Other services | 2015 |
| Chris Hazell Ltd | Professional & scientific | 2016 |
| Christina Lade Consulting Limited | Professional & scientific | 2015 |
| Christopher Stoakes Limited | Information & communication | 2011 |
| Church Extension Association(Incorporated)(The) | Other services | 1890 |
| Churchill Cooling Services Ltd | Construction | 2026 |
| Churchward Management Services Limited | Construction | 2020 |
| Ciccheteria Limited | Hospitality | 2025 |
| Ciel (Dean ST) Limited | Hospitality | 2011 |
| Ciel (Hackney) Limited | Hospitality | 2013 |
| Circle Law LLP | | 2018 |
| City Data Installations Limited | Information & communication | 2017 |
| City Moving & Storage Limited | Transport & logistics | 1986 |
| CJM Decor Limited | Construction | 2025 |
| Cjtd Limited | Construction | 2024 |
| CKF Property Holdings Ltd | Real estate | 2024 |
| Claire Fleming Limited | Information & communication | 2016 |
| Clarke HR Solutions Limited | Administrative & support | 2024 |
| Claverdon Real Estate Ltd | Real estate | 2025 |
| Clayhall Trading Company Limited | Real estate | 2026 |
| Clayton Hayes Limited | Real estate | 2024 |
| Clean Water Productions Limited | Construction | 2019 |
| Clever Productions Limited | Administrative & support | 2007 |
| CLH Psychological Services Ltd | Health & social care | 2023 |
| Cloud Atom Limited | Information & communication | 2021 |
| Cloud Colibri Ltd | Information & communication | 2017 |
| Cloud Delivery Ltd | Information & communication | 2020 |
| Cloud Thought Limited | Wholesale & retail | 2018 |
| Cloverleys Limited | Financial services | 2007 |
| CMC Craniosacral Limited | Health & social care | 2024 |
| CMR Shandwick Place Ltd | Real estate | 2023 |
| Cmtl Holdings Limited | Extraterritorial | 2022 |
| Coactive Health Limited | Health & social care | 2013 |
| Coastwell Associates Ltd | Professional & scientific | 2011 |
| Cobatt Consulting Services Limited | Information & communication | 2000 |
| Coco Nails Bar 78 Ltd | Other services | 2023 |
| Cognatus Ltd | Professional & scientific | 2022 |
| Cojarec International Sales Ltd | Manufacturing | 2015 |
| Colin Smythe Limited | Wholesale & retail | 1965 |
| Colle Consulting Ltd | Professional & scientific | 2012 |
| Collyer Adjusters Ltd. | Extraterritorial | 1998 |
| Collyer Claims Services Limited | Extraterritorial | 1994 |
| Collyers Fresh Limited | Financial services | 2015 |
| Collyers TMA Limited | Financial services | 1981 |
| Colter & ROE Limited | Wholesale & retail | 2016 |
| Colton-Chatto Ltd | Real estate | 2015 |
| Colwill International Ltd | Wholesale & retail | 2024 |
| Commsnet Solutions Limited | Information & communication | 2010 |
| Communikate Coaching and Training Ltd | Professional & scientific | 2022 |
| Communisys Ltd | Administrative & support | 2025 |
| Compassia Ltd | Financial services | 2023 |
| Compassrock Real Estate Ltd | Real estate | 2021 |
| Complete Audio Visual Limited | Other services | 2010 |
| Completely Ltd | Administrative & support | 2024 |
| Computer Performance International Limited | Information & communication | 1988 |
| Concept Edge Power Limited | Wholesale & retail | 2001 |
| Conduco Consulting Limited | Other services | 2003 |
| Conifers Care Ltd | Health & social care | 2006 |
| Coniston Day Limited | Administrative & support | 2012 |
| Connaught Strategies Limited | Administrative & support | 2012 |
| Construction AI Ltd | Information & communication | 2025 |
| Construction Industry Publications Limited | Information & communication | 1994 |
| Consultancy AI IO Ltd | Information & communication | 2026 |
| Contract Environmental Services Limited | Administrative & support | 2012 |
| Cookology Limited | Hospitality | 2016 |
| Cool Air Solutions Limited | Other services | 2015 |
| Cope Sands (Holdings) Limited | Real estate | 2021 |
| Core Simplicities Limited | Professional & scientific | 2012 |
| Coredrobe Ltd | Wholesale & retail | 2025 |
| Cormorant Ventures Limited | Professional & scientific | 1998 |
| Corne Van Mourik Plants Ltd | Wholesale & retail | 2021 |
| Corrib Property Ltd | Construction | 2023 |
| Cothall Consultancy Services Ltd | Professional & scientific | 2020 |
| Court House Salcombe Limited | Households | 2007 |
| COURT18 Tennis LLP | | 2018 |
| Couture Chairs Ltd | Manufacturing | 2016 |
| CP T/As ST Peters News Ltd | Wholesale & retail | 2019 |
| CR Construction Limited | Construction | 2025 |
| CR Fashion Trading Limited | Wholesale & retail | 2025 |
| Crabtree Electrical Industries Limited | Professional & scientific | 1919 |
| Cracked Eggs Holdings Limited | Financial services | 2025 |
| Crafted Stitch & Interiors Ltd | Wholesale & retail | 2016 |
| Crazy Drive Ltd | Transport & logistics | 2020 |
| Created by ME Limited | Professional & scientific | 2013 |
| Creative Intelligence Collective Limited | Professional & scientific | 2017 |
| Cremorne Nominees Limited | Professional & scientific | 1975 |
| Crest School of Motoring Limited | Education | 2011 |
| Crimson Software Limited | Information & communication | 2001 |
| Crisis Communications Limited | Professional & scientific | 2019 |
| Crispin Layfield Stunts Limited | Arts & recreation | 2012 |