| Cockermouth Tech Solutions Ltd | Wholesale & retail | 2025 |
| Cockton's Yard Management Company Limited | Households | 1986 |
| Codefit Consulting Limited | Information & communication | 2014 |
| Colin Stuart Limited | Other services | 2012 |
| Community Nuclear Power Limited | Professional & scientific | 2022 |
| Compton Industries Ltd | Agriculture & fishing | 2011 |
| Coniston Consultants Limited | Professional & scientific | 2005 |
| Copy-On Business Systems Limited | Wholesale & retail | 2006 |
| Cosmogony Ltd | Information & communication | 2026 |
| Cragg Farm Camping Pods Ltd | Hospitality | 2020 |
| Crayston Developments Ltd | Construction | 2022 |
| Create Golf Europe Limited | Professional & scientific | 2015 |
| Createc Ltd | Professional & scientific | 2010 |
| Creative Data Management Systems Ltd | Information & communication | 2024 |
| Crooked River Social Ltd | Hospitality | 2024 |
| Crossfit Stormbreaker Limited | Arts & recreation | 2019 |
| Crown OPS Ltd | Professional & scientific | 2019 |
| Crs-Fm Ltd | Administrative & support | 2025 |
| Crummock Consultants Limited | Professional & scientific | 2022 |
| CS Engineering (Cumbria) Limited | Administrative & support | 2014 |
| CS Project Services (Cumbria) Limited | Other services | 2014 |
| CTF Energy Limited | Professional & scientific | 2018 |
| Cumberland Football Association Limited | Arts & recreation | 2000 |
| Cumberland Interiors Limited | Wholesale & retail | 2018 |
| Cumberland Livestock Limited | Agriculture & fishing | 2013 |
| Cumberland Scaffolding Ltd | Construction | 2014 |
| Cumbria Airport Taxis Ltd | Transport & logistics | 2024 |
| Cumbria Airport Travel Ltd | Transport & logistics | 2024 |
| Cumbria Building Contractors Limited | Construction | 2019 |
| Cumbria Coal Limited | Wholesale & retail | 2018 |
| Cumbria Community Foundation | Administrative & support | 1999 |
| Cumbria Composite Decking and Timber Ltd | Wholesale & retail | 2020 |
| Cumbria Creatives Limited | Wholesale & retail | 2021 |
| Cumbria Golf Centre Limited | Arts & recreation | 2009 |
| Cumbria Livestock Limited | Agriculture & fishing | 2013 |
| Cumbria Ready VEG Ltd | Hospitality | 2020 |
| Cumbria SAW Service Limited | Manufacturing | 2003 |
| Cumbria Special Events Company Limited | Extraterritorial | 2012 |
| Cumbria Wills & Planning Ltd | Professional & scientific | 2022 |
| Cumbrian Baker Limited | Wholesale & retail | 2022 |
| Cumbrian Commissioning Ltd | Professional & scientific | 2023 |
| Cumbrian Livestock Limited | Agriculture & fishing | 2013 |
| Cunha Limited | Administrative & support | 2019 |
| Curb Clothing Ltd | Administrative & support | 2026 |
| D & D Abbott Investments Limited | Real estate | 2017 |
| D & K Cottage Management Limited | Administrative & support | 2019 |
| D P Rally Services Ltd | Professional & scientific | 2012 |
| D Whiteley Q S Services Limited | Professional & scientific | 2010 |
| D Wise Property Ltd | Real estate | 2026 |
| Dalton Park Ltd | Households | 2021 |
| Dalton Project & Programme Management Ltd | Administrative & support | 2018 |
| Dance and Fitness at Studio Nine C.I.C. | Health & social care | 2020 |
| Daniel Rourke Engineering and Surveying Ltd | Construction | 2022 |
| Darc Engineering Ltd | Professional & scientific | 2023 |
| Darkhouse Coffee Roasters Limited | Manufacturing | 2019 |
| Darrie Limited | Wholesale & retail | 2009 |
| Dash 31 Limited | Professional & scientific | 2024 |
| DB Electrical Cumbria Limited | Construction | 2024 |
| DB Project Solutions Ltd | Administrative & support | 2014 |
| DB1690 Limited | Professional & scientific | 2022 |
| Dclough Developments Limited | Real estate | 2024 |
| DEB Walker Equestrian Ltd | Other services | 2020 |
| Decking Design Limited | Construction | 2020 |
| Delnikky Limited | Hospitality | 2023 |
| Denton House Hostel Ltd | Hospitality | 2012 |
| Derventio Properties Limited | Real estate | 2024 |
| Derwent Air Rifles Limited | Wholesale & retail | 2021 |
| Derwent Frames Limited | Arts & recreation | 2003 |
| Derwent Groundworks Ltd | Construction | 2020 |
| Derwent Valley Building Limited | Construction | 2009 |
| Derwent Valley Projects Limited | Energy | 2023 |
| Derwent Walker Limited | Hospitality | 2021 |
| Dexx Holdings Ltd | Financial services | 2023 |
| Dgmd Solutions Limited | Other services | 2023 |
| Diane Gainey Limited | Arts & recreation | 2003 |
| Distinction by Design Joinery and Construction. Ltd | Construction | 2026 |
| DJG Regeneration Ltd | Construction | 2026 |
| DJJ Engineering Limited | Administrative & support | 2026 |
| DJR3 Ltd | Administrative & support | 2022 |
| DLB Commissioning Services Limited | Administrative & support | 2013 |
| DLB1690 Limited | Construction | 2026 |
| DMC70 Limited | Professional & scientific | 2017 |
| Dmci Consultancy Limited | Information & communication | 2026 |
| Double Dragon Engineering Limited | Professional & scientific | 2019 |
| Douglas Process Consultancy LLP | | 2024 |
| Dovenby Game Limited | Agriculture & fishing | 2015 |
| Dovenby Shoot Limited | Administrative & support | 2008 |
| Dovenby Sporting Club Limited | Agriculture & fishing | 2015 |
| DR SAM Rigby Facial Aesthetics Ltd | Health & social care | 2019 |
| DR VET Ltd | Financial services | 2026 |
| Dragonfly Access Limited | Mining & quarrying | 2023 |
| Drone Imagery Services Ltd | Professional & scientific | 2020 |
| Drystone Engineering Ltd. | Professional & scientific | 2016 |
| DSG Design Ltd | Professional & scientific | 2017 |
| DSM Consultancy (Cheshire) Limited | Information & communication | 2014 |
| DSM Partners Ltd | Professional & scientific | 2022 |
| Dyson Engineering Solutions Limited | Professional & scientific | 2026 |
| E M Professional Services Limited | Administrative & support | 2025 |
| E. W. & P. a. Nicholson Limited | Transport & logistics | 1985 |
| EA Renovations Limited | Construction | 2012 |