| Compass Building Consultancy Limited | Professional & scientific | 2020 |
| Compass-Services to Improve Health and Wellbeing | Health & social care | 1986 |
| Compincent Limited | Information & communication | 2015 |
| Complete Athlete Management Ltd | Arts & recreation | 2026 |
| Complete Building Solutions (Yorkshire) Limited | Construction | 2008 |
| Complete Caffe Limited | Hospitality | 2025 |
| Complete Cleaning (Yorkshire) Ltd | Administrative & support | 2024 |
| Complete Life Fitness Limited | Arts & recreation | 2018 |
| Complete Linen Services Ltd | Other services | 2024 |
| Complete Lite Solutions UK Ltd | Administrative & support | 2005 |
| Complete PLANS2BUILD Limited | Professional & scientific | 2011 |
| Complete Spray Solutions (UK) Limited | Wholesale & retail | 2023 |
| Complete Survey Solutions Limited | Construction | 2006 |
| Complete Utility Connections Ltd | Energy | 2025 |
| Complisoft Limited | Professional & scientific | 2004 |
| Complitech Ltd | Financial services | 2025 |
| Compow Limited | Professional & scientific | 2019 |
| Compton Court Management Company Limited | Households | 1999 |
| Comres Property Limited | Extraterritorial | 2016 |
| Comtelenic Ltd | Professional & scientific | 2022 |
| Comwell & Winston Limited | Professional & scientific | 2014 |
| Con-Strictors Air Ltd | Transport & logistics | 2025 |
| Conbrio Limited | Construction | 2017 |
| Concept Business Centre (York) Ltd | Administrative & support | 2026 |
| Concept Business Centre Ltd | Administrative & support | 2019 |
| Concept Games Limited | Other services | 1998 |
| Concept Hair Design & Beauty Limited | Other services | 2011 |
| Concept Presentation Solutions (Management) Limited | Administrative & support | 2014 |
| Concept Presentation Solutions Limited | Wholesale & retail | 2005 |
| Conceptiling (York) Limited | Construction | 2009 |
| Concorde Europe Limited | Administrative & support | 2001 |
| Concordia Street Management Company Limited | Households | 1999 |
| Condencure Ltd | Construction | 2012 |
| Condor Accountants Limited | Professional & scientific | 2019 |
| Condor Verde (UK) Trading Ltd | Manufacturing | 2025 |
| Conexo Solutions Limited | Administrative & support | 2004 |
| Coney Hill Farm Creamery Ltd | Manufacturing | 2024 |
| Coney Street III LLP | | 2020 |
| Coney Street V LLP | | 2022 |
| Confident Dental Care Ltd | Health & social care | 2023 |
| Confrere Building Control Limited | Professional & scientific | 2022 |
| Congregation of Jesus Trustee | Other services | 2013 |
| Coning Fertiliser Limited | Agriculture & fishing | 2011 |
| Coning Haulage Limited | Transport & logistics | 2016 |
| Connaught Court LLP | | 2017 |
| Connect Coolers Limited | Hospitality | 2009 |
| Connect Scaffolding (York) Ltd | Construction | 2024 |
| Connexin Therapeutics Group Limited | Professional & scientific | 2021 |
| Connexin Therapeutics Ltd | Professional & scientific | 2018 |
| Connexionsbuses Limited | Transport & logistics | 2016 |
| Connie and Friends Limited | Wholesale & retail | 2025 |
| Connoisseur Wines Ltd | Wholesale & retail | 2005 |
| Consaelting Ltd. | Professional & scientific | 2015 |
| Conscious Living Global Ltd | Professional & scientific | 2019 |
| Conserve Solutions UK Limited | Construction | 2014 |
| Consilium Construction Services Ltd | Professional & scientific | 2022 |
| Constable Vale (Hadleigh) Residents Management Company Limited | Households | 2024 |
| Constantine Cybersecurity Ltd. | Real estate | 2017 |
| Constantine House (York) Management Company Limited | Households | 2002 |
| Constellation Building & Joinery Limited | Construction | 2015 |
| Construct Interpretive Design Ltd | Administrative & support | 2007 |
| Construct Zero Consulting Limited | Professional & scientific | 2026 |
| Constructing Change CIC | Education | 2025 |
| Construction Automation Limited | Administrative & support | 2016 |
| Constructive Designs Ltd | Professional & scientific | 2007 |
| Constructright (York) Ltd | Construction | 2014 |
| Consulting TLC Limited | Information & communication | 2021 |
| Content Labs Ltd | Administrative & support | 2020 |
| Continuum (Entertainment) Limited | Arts & recreation | 1985 |
| Continuum (Loch Ness) Limited | Arts & recreation | 2018 |
| Contract Actuarial Resources Ltd | Financial services | 2008 |
| Contract Landscapes U.K. Limited | Construction | 1994 |
| Contract Services (Yorkshire) Limited | Wholesale & retail | 1972 |
| Control Partners (York) Ltd | Other services | 2005 |
| Convergence International Ltd | Information & communication | 2017 |
| Convertaloft Limited | Construction | 2016 |
| Convicted Vapes Ltd | Wholesale & retail | 2023 |
| Convoyr Ltd | Information & communication | 2026 |
| Conway Hospitality Ltd | Hospitality | 2023 |
| Conway Potter Limited | Hospitality | 2021 |
| COO Accelerator Limited | Professional & scientific | 2023 |
| Cook and Holman Ltd | Hospitality | 2026 |
| Cook Engineering Ltd | Professional & scientific | 2026 |
| Cook Property Group Limited | Real estate | 2019 |
| Cookham Professional Ltd | Professional & scientific | 2018 |
| Cookie's Cleaning Crew Ltd | Administrative & support | 2010 |
| Cooks Motor Co. (K.M.S.) Limited | Wholesale & retail | 1960 |
| Cool Computers Limited | Manufacturing | 2014 |
| Cool T Limited | Wholesale & retail | 2020 |
| Cooldaniel Holdings Limited | Real estate | 2022 |
| Coolinary London Ltd | Hospitality | 2020 |
| Cooltec Services (York) Limited | Energy | 2008 |
| Cooney & Sons Ltd | Construction | 1999 |
| Cooney's Enterprises Limited | Hospitality | 2021 |
| Cooper Architecture Limited | Professional & scientific | 2016 |
| Cooper King Distillery Ltd | Manufacturing | 2016 |
| Cooper Property (York) Ltd | Real estate | 2025 |
| Cooper Rail Limited | Professional & scientific | 1998 |
| Cooper Woods Electrical Ltd | Construction | 2018 |
| Coopers Marquees Property Limited | Real estate | 2024 |