| Construction Commercial Consulting Ltd | Construction | 2011 |
| Construction Commercial Management Limited | Construction | 2008 |
| Construction Contract Resolutions Ltd | Professional & scientific | 2015 |
| Construction Floor Systems (North) Limited | Construction | 2024 |
| Construction Floor Systems Limited | Construction | 2022 |
| Construction Maintenance & Labour Ltd | Construction | 2014 |
| Construction Results Limited | Construction | 2021 |
| Construction Setting OUT Limited | Construction | 2019 |
| Construction Site and Consultancy Services Ltd | Professional & scientific | 2011 |
| Constructionend Limited | Real estate | 1970 |
| Construo Consulting Ltd | Administrative & support | 2022 |
| Consultancy Based Solutions Ltd | Wholesale & retail | 2019 |
| Consultancy Works Limited | Professional & scientific | 2010 |
| CONSULTANCY32 Ltd | Information & communication | 2011 |
| Consultcarr Limited | Professional & scientific | 2026 |
| Consumers Unite Limited | Administrative & support | 2017 |
| Contact Centre Panel Limited | Professional & scientific | 2015 |
| Contact Holdings Ltd | Professional & scientific | 2021 |
| Contact Holds Ltd | Manufacturing | 2022 |
| Contemplative Fire | Other services | 2004 |
| Contemporary Gardens Ltd | Wholesale & retail | 2018 |
| Contend Ltd | Construction | 2024 |
| Content Corporation Ltd | Arts & recreation | 2011 |
| Content on Demand Ltd | Information & communication | 2010 |
| Content Perspective Limited | Administrative & support | 2023 |
| Contextul Holdings Limited | Information & communication | 2023 |
| Contextul Operations Limited | Information & communication | 2025 |
| Contimart Ltd | Wholesale & retail | 2025 |
| Continental Autos Ltd | Wholesale & retail | 2020 |
| Continental Games Ltd | Information & communication | 2019 |
| Continental Property Group Ltd | Real estate | 2023 |
| Continuous Entertainment Limited | Professional & scientific | 2023 |
| Contix CIC | Real estate | 2023 |
| Contourmusik Limited | Information & communication | 2022 |
| Contract Distributors Limited | Real estate | 1996 |
| Contract Flooring & Interiors (C.F.I.) Ltd | Administrative & support | 2005 |
| Contract Floors (Sheffield) Limited | Construction | 1993 |
| Contract Joinery Ltd | Construction | 2009 |
| Contract Joinery Projects Limited | Construction | 2024 |
| Contract Kitchens Limited | Construction | 1999 |
| Contractor JTB Ltd | Administrative & support | 2024 |
| Contractor Mate Limited | Other services | 2023 |
| Contractors for YOU Limited | Construction | 2015 |
| Converting Tissue Spares Ltd | Wholesale & retail | 2020 |
| Conway OFF Licence Limited | Wholesale & retail | 2024 |
| Cooinda Communications Limited | Professional & scientific | 2012 |
| Cook 'N' Dine Limited | Professional & scientific | 1996 |
| Cook Brown Building Control Ltd | Professional & scientific | 2013 |
| Cook Defence Systems Limited | Wholesale & retail | 2009 |
| Cook Precision Ceramic Castings Limited | Manufacturing | 2025 |
| Cooke & Knight (Builders) Limited | Construction | 1973 |
| Cooke and Deaton Table Tennis Ltd | Arts & recreation | 2024 |
| Cooke Medical Services Limited | Health & social care | 2015 |
| Cookihut Limited | Hospitality | 2021 |
| Cool Head Commercial Solutions Limited | Professional & scientific | 2019 |
| Coolcore Limited | Professional & scientific | 2026 |
| Cooling and Heating Space Limited | Construction | 2021 |
| Coolnagour UK Limited | Information & communication | 2014 |
| Cooper & Turner Limited | Manufacturing | 2000 |
| Cooper Advanced Practice Limited | Health & social care | 2019 |
| Cooper Commissioning Limited | Construction | 2016 |
| Cooper Finch Associates Limited | Professional & scientific | 2002 |
| Cooper Web Solutions Ltd | Information & communication | 2016 |
| Coopermatic Limited | Wholesale & retail | 2014 |
| Coopers Tours (Lincolnshire) Limited | Transport & logistics | 1995 |
| Coopers Tours Limited | Transport & logistics | 1996 |
| Coops Embs Limited | Construction | 2010 |
| Coops Group Limited | Professional & scientific | 2024 |
| Coops Renewables Limited | Construction | 2023 |
| Coops Switchgear Limited | Construction | 2024 |
| Coordinated Risk Solutions 2017 Limited | Professional & scientific | 2017 |
| Coorie Inns & Bars Ltd | Hospitality | 2022 |
| Copa Caffe Ltd | Hospitality | 2021 |
| Copa Copa Limited | Administrative & support | 2005 |
| Copacetic Gentlemen's Grooming Ltd | Other services | 2015 |
| Copcutt Consultancy Ltd | Wholesale & retail | 2014 |
| Copia Hallam Limited | Professional & scientific | 2024 |
| Copia Properties Ltd | Real estate | 2026 |
| Copley Couriers Limited | Transport & logistics | 2001 |
| Copper Beech View Management Company Ltd | Real estate | 2023 |
| Copper FOX Electrical Ltd | Construction | 2018 |
| Copper Moon Digital Ltd | Information & communication | 2024 |
| Copper POT Hospitality Ltd | Hospitality | 2022 |
| Copper Street Ltd | Hospitality | 2017 |
| Copperfields Health Care Limited | Health & social care | 2018 |
| Coppertop Jewellery Ltd | Manufacturing | 2024 |
| Copster Ventures Limited | Education | 2026 |
| Coptain Properties Limited | Real estate | 2011 |
| Coptercrafters Ltd | Information & communication | 2023 |
| Copytec Limited | Administrative & support | 2003 |
| Copyworld Limited | Administrative & support | 1989 |
| COR Cordium Limited | Professional & scientific | 2018 |
| COR Trans Limited | Transport & logistics | 2019 |
| Coral Compass Ltd | Agriculture & fishing | 2018 |
| Coral Murmur Ltd | Wholesale & retail | 2025 |
| Corazon Capital Limited | Health & social care | 2004 |
| Corazon Estates Limited | Health & social care | 2004 |
| Corazon Health Care Investments Limited | Health & social care | 2001 |
| Corbygate Limited | Real estate | 2025 |
| Cordel Property Ltd | Construction | 2020 |