| Complete Contract Management Ltd | Construction | 2024 |
| Complete Heating & Bathrooms Limited | Construction | 2007 |
| Complete Plant Inspection Ltd | Professional & scientific | 2026 |
| Complete Training Ltd | Administrative & support | 2024 |
| Complex Engine Limited | Information & communication | 2012 |
| Complymarket Ltd | Information & communication | 2026 |
| Compute One Ltd | Information & communication | 2019 |
| CON Air Northern Limited | Energy | 2022 |
| Concept (Yorkshire) Limited | Construction | 2012 |
| Concept Applications Limited | Transport & logistics | 2007 |
| Concept Recruitment Group Limited | Administrative & support | 2006 |
| Concept Recruitment Solutions Limited | Extraterritorial | 2010 |
| Concorde Property Limited | Real estate | 2012 |
| Concrete Posts and Panels Limited | Administrative & support | 2015 |
| Concrete Xpress Limited | | 2008 |
| Conexus Healthcare C.I.C. | Administrative & support | 2017 |
| Confi-Smile Care Ltd | Health & social care | 2016 |
| Connect Electrical Yorkshire Ltd | Construction | 2022 |
| Connect Professional Services Limited | Information & communication | 2026 |
| Connect VM Limited | Other services | 2019 |
| Connect Women in BIZ Ltd | Professional & scientific | 2026 |
| Connected Ministries | Other services | 2010 |
| Connex International Services LP | | 2009 |
| Conor Jordan Limited | Health & social care | 2019 |
| Conservatory Outlet Group Limited | Financial services | 2022 |
| Conservatory Outlet Holdings Limited | Construction | 2014 |
| Conservatory Outlet Limited | Construction | 2025 |
| Conservatory Roofs 4 U Ltd | Other services | 2017 |
| Construction & Cleaning Specialists Limited | Construction | 2020 |
| Consulo Financial Planning Limited | Financial services | 2014 |
| Consultancy OT Ltd | Administrative & support | 2022 |
| Consultante Limited | Professional & scientific | 2025 |
| Consumer Hub Limited | Administrative & support | 2017 |
| Containers Directs UKK Ltd | Financial services | 2026 |
| Containment Control Technology Ltd | Professional & scientific | 2012 |
| Continental Cash Collections Limited | Administrative & support | 1982 |
| Contractswise Limited | Professional & scientific | 2007 |
| Control Communications Limited | Energy | 2024 |
| Convenience Foods Limited | Manufacturing | 1988 |
| Conversation Shed Limited | Arts & recreation | 2022 |
| Convertify Ltd | Information & communication | 2024 |
| Converting Nation Sales Limited | Manufacturing | 2024 |
| Convinco Barbers Limited | Other services | 2020 |
| Conway Retail Limited | Wholesale & retail | 2018 |
| Cooper & Cutt Estate Agents Ltd | Real estate | 2019 |
| Cooper & Westgate Co. Holdings Ltd | Financial services | 2025 |
| Cooper & Westgate Co. Ltd | Construction | 2003 |
| Cooper & Westgate Developments Ltd | Real estate | 2017 |
| Cooper & Wood Limited | Construction | 2012 |
| Cooper - Close Electrical Contractors Limited | Construction | 2012 |
| Cooper Properties (Yorkshire) Ltd | Households | 2026 |
| Coopers Renewals Ltd | Construction | 2018 |
| Copper Technology Holdings Ltd | Financial services | 2017 |
| Copper Work Commercial Limited | Wholesale & retail | 2018 |
| Copperfield House Residents Management Company Limited | Households | 2010 |
| Corarima Kitchen Ltd | Wholesale & retail | 2026 |
| Corarima Ltd | Manufacturing | 2018 |
| Corditek Ltd | Information & communication | 2026 |
| Core Aesthetics Limited | Other services | 2016 |
| Core Medical Clinics Limited | Health & social care | 2018 |
| Core Rewards Ltd | Administrative & support | 2023 |
| Corescale Ltd | Information & communication | 2025 |
| Corespark Electrical Ltd | Construction | 2025 |
| Coretek Properties Limited | Real estate | 2016 |
| Corewards Ltd | Administrative & support | 2023 |
| Cornerstone Invesments Ltd | Real estate | 2024 |
| Cornmill 62 Ltd | Wholesale & retail | 2017 |
| Correct Business Solutions Ltd. | Professional & scientific | 2025 |
| Corrigans Barbers Ltd | Other services | 2021 |
| Corrin Properties Ltd | Real estate | 2026 |
| Corsem Limited | Wholesale & retail | 2025 |
| Cortex Advisory Group Limited | Professional & scientific | 2006 |
| Coryl Ltd | Information & communication | 2007 |
| COS West Services Ltd | Transport & logistics | 2023 |
| Cosichem UK Ltd. | Professional & scientific | 2018 |
| Cosmic Property Solutions Ltd | Real estate | 2022 |
| Cosmo Equity Limited | Financial services | 2005 |
| Costca Limited | Wholesale & retail | 2025 |
| Cosy Cleaning Services Limited | Administrative & support | 2024 |
| Cottingham (Waltham) Limited | Wholesale & retail | 2005 |
| Cotton & Rose Ltd | Other services | 2026 |
| Cottons Spin Ltd | Other services | 2024 |
| Coulman Property Development Limited | Construction | 2015 |
| Countryside Carpentry & Joinery Limited | Manufacturing | 2025 |
| Countrywide Energy Performance Limited | Real estate | 2008 |
| Courthaus Ltd | Real estate | 2022 |
| Courtley West Limited | Professional & scientific | 2007 |
| Courtyard Waste Management Ltd | Households | 2022 |
| Cowell Holdings Limited | Financial services | 2026 |
| COX Digital Ltd | Information & communication | 2021 |
| Coxley Construction Ltd | Construction | 2021 |
| Coxley Engineering Limited | Professional & scientific | 2017 |
| Coxley Tree Care Ltd | Professional & scientific | 2014 |
| Coxs Boxes and Packaging Ltd | Administrative & support | 2026 |
| Coxyco Commercial Consulting Ltd | Professional & scientific | 2025 |
| Cozy Comfort Yorkshire Ltd | Manufacturing | 2025 |
| Cozy Spine Ltd | Manufacturing | 2025 |
| CP Auto Services Ltd | Professional & scientific | 2010 |
| CPH Media Limited | Information & communication | 2024 |
| CPL Electrical Services (Halifax) Limited | Professional & scientific | 1999 |