| Coquet Health Supplements Ltd | Wholesale & retail | 2023 |
| Coquet Home Improvements Ltd | Construction | 2022 |
| Coquet Island Shellfish Limited | Manufacturing | 2003 |
| Coquet Valley Homes Ltd | Real estate | 2020 |
| Coquet Valley Trails Ltd | Arts & recreation | 2025 |
| Coquetdale Care Ltd | Health & social care | 2023 |
| Coquetdale Timber Limited | Agriculture & fishing | 2023 |
| Corbridge Delicatessens Limited | Hospitality | 2007 |
| Core Tooling Solutions Ltd | Professional & scientific | 2017 |
| Cottingburn Limited | Real estate | 2013 |
| Country Cottages Ltd | Real estate | 2024 |
| Countryside Building & Civil Engineering Contractors Ltd. | Construction | 2012 |
| County Craft Homes Limited | Construction | 2018 |
| Cowell Academy of Stage & Television Ltd | Arts & recreation | 2019 |
| Cowling Technologies Ltd. | Information & communication | 2014 |
| Cowry Property Ltd | Real estate | 2018 |
| Coyote Properties Ltd | Real estate | 2019 |
| CP Property Holdings Limited | Real estate | 2019 |
| CPB Consultants Limited | Professional & scientific | 2014 |
| CPS Scaffolding Limited | Construction | 2007 |
| CPY North Limited | Real estate | 2025 |
| Crafty Computing Limited | Education | 2016 |
| Craighill Molineux Ltd | Other services | 2016 |
| Craightelecoms Ltd | Information & communication | 2025 |
| Craik Park Events Ltd | Hospitality | 2024 |
| Cramlington Insurance Services LLP | | 2005 |
| Crawhall Mediation Limited | Professional & scientific | 2022 |
| Credence Brewing Ltd | Manufacturing | 2015 |
| Creighton House Estates Limited | Real estate | 2022 |
| Crichton Wills Trusts & Probate Limited | Financial services | 2011 |
| Croft Road Residents Limited | Professional & scientific | 1995 |
| Cromwell Close Management Limited | Water & waste | 1995 |
| Cross Trading Co Ltd | Wholesale & retail | 2026 |
| Crowcroft Bros Landscaping Limited | Administrative & support | 2024 |
| Crowned Lion Ltd | Administrative & support | 2025 |
| Crowther Ballantyne Associates Limited | Administrative & support | 2000 |
| Crust and Castles Ltd | Hospitality | 2018 |
| CS4 Consulting Ltd | Professional & scientific | 2010 |
| Csamble Ltd | Hospitality | 2025 |
| Cslp Hospitality Ltd | Hospitality | 2025 |
| CSP Vault Ltd | Professional & scientific | 2021 |
| CT Consult Limited | Professional & scientific | 2025 |
| CTP Creative Imaging Limited | Professional & scientific | 2026 |
| Culsmore Limited | Construction | 1987 |
| CULTIV8 Business Ltd | Professional & scientific | 2019 |
| Cunningham and Hristov Limited | Health & social care | 2025 |
| Curious Squirrel Zine Ltd | Information & communication | 2023 |
| Curson-Thorne Developments Ltd | Construction | 2024 |
| Cusimano's Bolting Tech Ltd | Professional & scientific | 2022 |
| Custom Garden Rooms Ltd | Construction | 2020 |
| CV Writing Hub Ltd | Other services | 2020 |
| CWH Gray Ltd | Professional & scientific | 2024 |
| Cyber Controls.Io Ltd | Information & communication | 2022 |
| Cycling 4 Everyone (North East) Limited | Administrative & support | 2019 |
| D & K Swan Limited | Real estate | 1968 |
| D a Johnstone Plant Hire Limited | Administrative & support | 2006 |
| D J Turnbull Contracting Ltd | Agriculture & fishing | 2017 |
| D Mcmillan Limited | Administrative & support | 2015 |
| D. R. Retail Limited | Wholesale & retail | 2002 |
| DAB Geotechnics Ltd | Mining & quarrying | 2013 |
| Dacre Point Ltd | Professional & scientific | 2023 |
| Dacre Street Developments Glanton Limited | Administrative & support | 2021 |
| Dacre Street Developments Glanton Two Limited | Administrative & support | 2022 |
| Dacre Street Developments Great Whittington Limited | Construction | 2024 |
| Dacre Street Developments Limited | Construction | 2015 |
| Dacre Street Developments Morpeth Limited | Administrative & support | 2016 |
| Dacre Street Developments Properties Limited | Administrative & support | 2016 |
| Dampfix North East Ltd | Construction | 2024 |
| DAN Slone Ltd | Professional & scientific | 2021 |
| Dance Street Limited | Wholesale & retail | 2023 |
| Daniel Carey Ltd | Professional & scientific | 2010 |
| Daniel Scrimshaw Professional Bolting Services Limited | Mining & quarrying | 2015 |
| Danya Finance Ltd | Construction | 2024 |
| Danya Investments Ltd | Real estate | 2015 |
| Darren James Limited | Administrative & support | 2022 |
| Data Dodgems Ltd | Information & communication | 2026 |
| David Curry Groundworks Ltd | Construction | 2005 |
| David Douglas Legal Services Ltd | Professional & scientific | 2025 |
| David Young Training and Consultancy Ltd | Administrative & support | 2018 |
| Dawn@Harpers Limited | Real estate | 2023 |
| Dazton Technical Ltd | Professional & scientific | 2018 |
| DB Electrical Limited | Construction | 2016 |
| DBS Domains Ltd | Information & communication | 2011 |
| DCM Medical Limited | Health & social care | 2025 |
| DCT Health Consulting Limited | Administrative & support | 2007 |
| DE Merley Construction Limited | Construction | 2026 |
| Deadly Detailing Ltd | Administrative & support | 2021 |
| Deja BRU Coffee Ltd | Hospitality | 2025 |
| Dejmaxx Ltd | Wholesale & retail | 2023 |
| Delessert DE Maligny LLP | | 2009 |
| Dellastrada Ltd | Professional & scientific | 2025 |
| Delopex Ltd | Professional & scientific | 2020 |
| Delph Tax Consultants Limited | Professional & scientific | 2014 |
| Delta Umbra Limited | Energy | 2020 |
| Dene View Management Company Limited | Households | 1996 |
| Derekb Ltd | Information & communication | 2021 |
| Derwent Logs Ltd | Wholesale & retail | 2022 |
| Descent World Limited | Information & communication | 2015 |
| Designer Hosiery Limited | Wholesale & retail | 2026 |
| Deuchar Park Consulting Ltd | Information & communication | 2015 |