| CONSULT4TECH Ltd | Manufacturing | 2026 |
| Consultancee Ltd | Professional & scientific | 2025 |
| Consultancy NB Limited | Professional & scientific | 2016 |
| Consultant Advisory Services Limited | Professional & scientific | 2025 |
| Consultavi Ltd | Administrative & support | 2014 |
| Consulting@Jenniferdunne Ltd | Professional & scientific | 2015 |
| Contact Cables Limited | Administrative & support | 2008 |
| Contagious DJS Ltd | Other services | 2016 |
| Conte Conveyancing Limited | Professional & scientific | 2016 |
| Continental Publishing Ltd | Information & communication | 2023 |
| Continual Solutions Limited | Information & communication | 2024 |
| Contractauditline Limited | Administrative & support | 2009 |
| Controlica Ltd | Manufacturing | 2024 |
| Controltech Automation Limited | Professional & scientific | 2024 |
| Convive Limited | Administrative & support | 2015 |
| Cook & SON Carpentry Ltd | Construction | 2015 |
| Cook Building Services Ltd | Construction | 2014 |
| Cook Close Management Company Limited | Real estate | 2016 |
| Cooke Holdings Ltd | Real estate | 2018 |
| Cookes Meadow Management Company Limited | Households | 2019 |
| Cooking on Fire Limited | Administrative & support | 2020 |
| Cooking Thyme Ltd | Wholesale & retail | 2003 |
| Cookland Communications Ltd | Construction | 2012 |
| Cook’S Project Management Ltd | Professional & scientific | 2024 |
| Cool Tots Music Limited | Extraterritorial | 2025 |
| Coolchalis Limited | Real estate | 1983 |
| Coombes Place (Rickmansworth) Management Company Limited | Households | 2002 |
| Coombs (Bedford) Limited | Professional & scientific | 1999 |
| Coombs Healthcare Solutions Ltd | Health & social care | 2008 |
| Coombs Ventures Ltd | Real estate | 2020 |
| Cooper Beard Estate Agency Limited | Real estate | 1990 |
| Cooper Edwards Fencing Limited | Administrative & support | 2017 |
| Cooper Wallace Limited | Real estate | 2016 |
| Coopers (Essex) Limited | | 1984 |
| Coopers Commercials Ltd | Manufacturing | 2025 |
| Copestone Copywriters Limited | Professional & scientific | 2006 |
| Copperwheat Media Ltd | Information & communication | 2024 |
| Coprime Limited | Information & communication | 2003 |
| Copy Cathy Ltd | Professional & scientific | 2019 |
| Copybox Document Systems Limited | Administrative & support | 2017 |
| Copycare Digital Solutions Ltd | Administrative & support | 2017 |
| Coralhigh Ltd | Health & social care | 2025 |
| Corby Balti Ltd | Hospitality | 2018 |
| Corby Masala Ltd | Hospitality | 2015 |
| Cordial Support Limited | Health & social care | 2020 |
| Core Four Limited | Information & communication | 2016 |
| Core Performance Ltd. | Arts & recreation | 2013 |
| Core Performance Memberships Limited | Arts & recreation | 2014 |
| Core Performance Prep Limited | Hospitality | 2023 |
| Core-Nutrition Limited | Wholesale & retail | 2014 |
| Coresight Research Limited | Professional & scientific | 2018 |
| Coreups Limited | Construction | 2018 |
| Corewood Solutions Ltd | Wholesale & retail | 2025 |
| Coriander Fusion Limited | Hospitality | 2022 |
| Corinthian Holdings Ltd | Financial services | 2017 |
| Cork & Co Wills Limited | Administrative & support | 2025 |
| Cornavin Watches Ltd | Wholesale & retail | 2018 |
| Corner Shop (Fordend Road) Limited | Wholesale & retail | 2016 |
| Cornerstone Axis Limited | Health & social care | 2026 |
| Cornerstone International Industries London Limited | Professional & scientific | 2020 |
| Cornland Ltd | Construction | 2015 |
| Corpinex Ltd | Financial services | 2012 |
| Corporate Dynamism Limited | Manufacturing | 2019 |
| Corporate Real Estate Holdings Ltd | Real estate | 1996 |
| Corporate Suites Ltd | Real estate | 2012 |
| Cortellan Limited | Construction | 2025 |
| Cortuf Group Limited | Financial services | 2020 |
| Cortuf International Limited | Manufacturing | 2022 |
| Corwell Developments Limited | Construction | 2017 |
| Corycatering Limited | Hospitality | 2020 |
| COS Glazing Services Limited | Construction | 2013 |
| Cosanostra Design Limited | Professional & scientific | 2005 |
| Cosche London Ltd | Wholesale & retail | 2019 |
| Coshmore Estates Ltd | Real estate | 2017 |
| Cosmick Limited | Wholesale & retail | 2020 |
| Cossmin Ltd | Transport & logistics | 2018 |
| Costan Services Ltd | Transport & logistics | 2018 |
| Costante Ltd | Real estate | 2015 |
| Cosyhome Heating Solutions Limited | Construction | 2026 |
| Cote Ventures Limited | Information & communication | 2012 |
| Cotech Trading (GB) Limited | Other services | 1991 |
| Cotk Limited | Professional & scientific | 2018 |
| Cotrain Ltd | Professional & scientific | 2019 |
| Cottenham Consultancy Limited | Professional & scientific | 2014 |
| Cotter Plant and Civil Engineering Ltd | Construction | 2013 |
| Cottle & Richardson Limited | Hospitality | 2011 |
| Cotton END Developments Limited | Administrative & support | 2019 |
| Cottonmill Linen Ltd | Other services | 2008 |
| Coulter Consulting Ltd | Professional & scientific | 2011 |
| Countess Way Management Company Limited | Households | 2016 |
| Country Properties Lettings LP | | 2011 |
| Country UK Limited | Extraterritorial | 2004 |
| Country Vehicles (Flitwick) Limited | Wholesale & retail | 2006 |
| Countryside Building Services Limited | Construction | 2022 |
| Countryview (Warkton) Limited | Health & social care | 1998 |
| Countrywide Mixer Hire Ltd | Administrative & support | 2017 |
| Countwise Europe Limited | Extraterritorial | 2013 |
| County Property Investment Company Limited(The) | Real estate | 1891 |
| County Style Ltd. | Wholesale & retail | 2025 |
| Courtcraft Advocate Ltd | Education | 2026 |