| Crystal Water Group Limited | Water & waste | 2020 |
| CS Brickwork Ltd | Construction | 2024 |
| CS Chinese Takeaway Ltd | Hospitality | 2022 |
| CS Event Solutions Ltd | Hospitality | 2023 |
| CS2 Property Development Ltd | Real estate | 2024 |
| CSE Engineering Contractors Ltd | Professional & scientific | 2025 |
| CSE Financial Services (North) Ltd | Financial services | 2011 |
| CSG Property Developments Ltd | Real estate | 2023 |
| CSJ Electrical York Ltd | Construction | 2022 |
| CSK Race Exhausts Limited | Manufacturing | 2009 |
| CSS Cleaners Limited | Administrative & support | 2025 |
| CST Property Limited | Real estate | 2018 |
| Cstg Games Ltd | Information & communication | 2024 |
| Csti (Coherent Science Technology International) Ltd | Professional & scientific | 2024 |
| CT Software Consultancy Ltd | Extraterritorial | 2018 |
| CTE Resourcing Ltd | Professional & scientific | 2025 |
| Cteson Limited | Health & social care | 2025 |
| CTM Capital Ltd | Real estate | 2021 |
| CTM Capital Partners Ltd | Real estate | 2021 |
| Ctofullstack Limited Partnership | | 2019 |
| CUB3 Limited | Real estate | 2005 |
| CUBE7 Engineering Ltd | Professional & scientific | 2017 |
| Cubist Solutions Ltd | Extraterritorial | 2018 |
| Cucktec Limited | Manufacturing | 2009 |
| Cuil Ltd | Administrative & support | 2016 |
| Cultivate Kindness Ltd | Education | 2022 |
| Cultural Connections York CIC | Hospitality | 2023 |
| Cumani Promotions Ltd | Information & communication | 2008 |
| Cumberland Comms Limited | Information & communication | 2005 |
| Cumberland House (York) Limited | Hospitality | 2025 |
| Cumberland House LLP | | 2016 |
| Cumbria Parking Services Ltd | Administrative & support | 2015 |
| Cummins Young Limited | Professional & scientific | 2011 |
| Cundall Manor Limited | Education | 1972 |
| Cunliffe Productions Limited | Arts & recreation | 1998 |
| CUP & Box Ltd | Administrative & support | 2025 |
| Cupa-Burton Group Limited | Wholesale & retail | 2008 |
| Cupit Farming Limited | Agriculture & fishing | 2012 |
| Cuppa Haven Ltd | Hospitality | 2024 |
| Curatus Arts Limited | Arts & recreation | 2023 |
| Cured Delicatessen Ltd | Hospitality | 2026 |
| Curious Insights Limited | Professional & scientific | 2024 |
| Curious Monkey Business Limited | Administrative & support | 2024 |
| Curlewis Limited | Households | 2024 |
| Curmudgeon Limited | Professional & scientific | 2020 |
| Curo York Ltd | Health & social care | 2021 |
| Curry & Chaat Company Limited | Manufacturing | 2025 |
| Curtain Room Interior Design Limited | Manufacturing | 2017 |
| Curzon Consulting Group Limited | Professional & scientific | 2025 |
| Curzon Consulting Holdings Limited | Professional & scientific | 2024 |
| Cusker Consultancy Limited | Other services | 2014 |
| Cussons & Storey Ltd | Professional & scientific | 2019 |
| Cussons Plumbing & Heating Ltd | Construction | 2024 |
| Custard Consulting Limited | Information & communication | 2020 |
| Custodia RMS Ltd | Information & communication | 2026 |
| Custom Plates Yorkshire Ltd | Wholesale & retail | 2025 |
| Customer Centric Ltd | Information & communication | 2021 |
| Customer Experience Improvement Limited | Professional & scientific | 2016 |
| Cusworth Container Services Limited | Transport & logistics | 2023 |
| CUT & Go (York) Ltd | Other services | 2024 |
| CUT by Design Ltd | Wholesale & retail | 2022 |
| CUT Loose Media Ltd | Information & communication | 2025 |
| CUT the Mustard HR Ltd | Professional & scientific | 2016 |
| Cutting Edge Joinery and Building Ltd | Construction | 2018 |
| CVC Projects Limited | Real estate | 2025 |
| CW Scaffolding & Property Services York Ltd | Construction | 2025 |
| CW Sound Production Limited | Information & communication | 2017 |
| CW72 Ltd | Professional & scientific | 2025 |
| CWB Decorators Ltd | Construction | 2023 |
| Cwrt Y Llwyfen (Johnstown) Management Company Limited | Households | 2015 |
| CXE City Limited | Professional & scientific | 2014 |
| CY Fencing York Ltd | Administrative & support | 2026 |
| Cybake Limited | Information & communication | 2014 |
| Cyber PIP Ltd | Information & communication | 2025 |
| Cyber Risk Associates Ltd | Information & communication | 2017 |
| Cyclaire Ltd | Wholesale & retail | 1998 |
| Cycle Heaven Limited | Wholesale & retail | 2003 |
| Cycle Secure Limited | Wholesale & retail | 2017 |
| Cyclestreet (York) Limited | Wholesale & retail | 2010 |
| Cyclicality Ltd | Financial services | 2017 |
| Cyclops Components Limited | Professional & scientific | 2000 |
| Cygnet Grange (Swanmore) Residents Management Company Limited | Households | 2023 |
| Cynergi IT Consulting Ltd | Information & communication | 2013 |
| Cynergy Engineering Limited | Manufacturing | 2012 |
| Cynosure Executive Search Limited | Administrative & support | 2023 |
| Cyrus Computer Consultants Limited | Information & communication | 1999 |
| D & C Watson Properties Ltd | Real estate | 2023 |
| D & D Window Centre York Ltd | Manufacturing | 2023 |
| D & E (York) Ltd | Administrative & support | 2003 |
| D & F Rustique Limited | Hospitality | 2008 |
| D & G Brickwork Group Ltd | Construction | 2025 |
| D & K Limited | Real estate | 2026 |
| D & K Painting Ltd | Construction | 2013 |
| D & S Electrical Services Yorkshire Limited | Construction | 2019 |
| D & S Retail Limited | Real estate | 2000 |
| D a Dowkes Electrical Ltd | Construction | 2003 |
| D a Oldfield Limited | Manufacturing | 1996 |
| D B Engineering (Ripon) Limited | Manufacturing | 2005 |
| D Barker Building & Joinery Ltd | Construction | 2019 |
| D Burnett Site Services Limited | Construction | 2010 |