| Crown Security Systems SSR Ltd | Administrative & support | 2020 |
| CS Access Services Ltd | Construction | 2025 |
| CSE Spray Solutions Ltd | Construction | 2022 |
| CSE Wind Solutions Ltd | Professional & scientific | 2025 |
| Csmuk (1995) Limited | Information & communication | 2012 |
| CSR Technical Services Limited | Professional & scientific | 2026 |
| CT Cleaning Ltd | Administrative & support | 2024 |
| CTG Limited | Manufacturing | 2008 |
| Curb Appeal Northern Ltd | Construction | 2025 |
| CW Property Ltd | Real estate | 2023 |
| CXB Consulting Limited | Professional & scientific | 2025 |
| Cygnet Family Law Limited | Professional & scientific | 2009 |
| D & D Sandwich Bar Ltd | Hospitality | 2024 |
| D & G Properties (NE) Ltd | Real estate | 2024 |
| D & R Development Solutions Limited | Construction | 2012 |
| D B Exterior Maintenance Ltd | Administrative & support | 2026 |
| D D L Properties Limited | Real estate | 2008 |
| D J Tucker Property Services Limited | Construction | 2015 |
| D J Underwood Plumbing and Heating Limited | Construction | 2012 |
| D Loudon Cctv & Network Solutions Ltd | Administrative & support | 2021 |
| D&G Insurance Services Limited | Financial services | 2018 |
| D&R Coatings Ltd | Construction | 2018 |
| D. B. R. Retail Limited | Wholesale & retail | 2016 |
| D.D.Design Ltd | Professional & scientific | 2005 |
| D.E.N.T Management Consultancy Ltd | Professional & scientific | 2025 |
| D.J Property Renovations Ltd | Construction | 2019 |
| D.J. Tucker Limited | Real estate | 1980 |
| D.S.Paterson Ltd | Transport & logistics | 2023 |
| DAB 3 Property Investments Limited | Real estate | 2017 |
| Dales Mechanical & Maintenance Ltd | Wholesale & retail | 2021 |
| DAN Sillett Theatricals Limited | Arts & recreation | 2023 |
| Danny Hart Descend Bike Park Limited | Arts & recreation | 2022 |
| Danu Retail Limited | Wholesale & retail | 2015 |
| Dare to Dream Properties Limited | Real estate | 2020 |
| David Tripp Inspection Services Limited | Manufacturing | 2019 |
| DE Boiz Limited | Manufacturing | 2011 |
| DECOR8 North East Limited | Construction | 2017 |
| Decore of Decay Ltd | Wholesale & retail | 2026 |
| Demonfish Ltd. | Information & communication | 2017 |
| Depot Connect International Limited | Financial services | 2016 |
| Depot Connect International UK Limited | Financial services | 2016 |
| Dermalogix Limited | Education | 2025 |
| Design Storm Distribution Ltd | Wholesale & retail | 2023 |
| Designer Playground Ltd | Wholesale & retail | 2019 |
| Dessert POD Redcar Ltd | Wholesale & retail | 2023 |
| Dhami & Co Ltd | Wholesale & retail | 2019 |
| DI Mare Pizza Ltd | Hospitality | 2025 |
| Dialup Ltd | Wholesale & retail | 2022 |
| Direct Beds Stockton Ltd | Wholesale & retail | 2019 |
| Direct Lift Solutions Limited | Manufacturing | 2010 |
| Discipline 365 Limited | Wholesale & retail | 2020 |
| Discipline Accountancy Limited | Professional & scientific | 2023 |
| Discipline Finance Limited | Financial services | 2023 |
| Discipline Group Limited | Financial services | 2023 |
| Discipline Legal Limited | Information & communication | 2023 |
| Discipline Limited | Other services | 2017 |
| Discipline Sports Limited | Wholesale & retail | 2023 |
| Discipline Strength 2 Succeed Community Interest Company | Health & social care | 2024 |
| Discovery DEN Daycare Ltd. | Education | 2023 |
| Dixon Designs Limited | Administrative & support | 2011 |
| DJE Safety Services Ltd | Construction | 2025 |
| DK Property Renovations Limited | Real estate | 2024 |
| DMB Bentley and Sons Ltd | Construction | 2021 |
| DMP Engineering Services Ltd | Construction | 2024 |
| Dorgan Barker Healthcare Ltd | Professional & scientific | 2025 |
| Dorgan Holdings Ltd | Real estate | 2021 |
| Dormanstown Take Away Ltd | Hospitality | 2025 |
| Dowle Properties Ltd | Real estate | 2005 |
| DP Support Services C.I.C. | Financial services | 2011 |
| DPJ Lettings Limited | Real estate | 2024 |
| DR Lifting Solutions Ltd | Construction | 2025 |
| Dragon Quality Services Ltd | Professional & scientific | 2013 |
| Dria Ltd | Construction | 2025 |
| Drury Safety Ltd | Professional & scientific | 2025 |
| Drurys Engineering Services Limited | Professional & scientific | 2023 |
| Duco Digital Ltd | Information & communication | 2018 |
| Dunny Limited | Wholesale & retail | 2025 |
| Durance Cleaning Services Limited | Administrative & support | 2012 |
| Dutch Brothers Property Ltd | Real estate | 2023 |
| DVS Autos Limited | Administrative & support | 2007 |
| Dynamic Homecare Services Limited | Health & social care | 2022 |
| Dynamic NE Property Ltd | Real estate | 2024 |
| E L Denney & SON Limited | Wholesale & retail | 2008 |
| E&L Consultancy (NE) Ltd | Professional & scientific | 2022 |
| E.Alb Properties Limited | Construction | 2024 |
| E.Spencer Telecom Ltd | Information & communication | 2025 |
| East Cleveland Community Radio Limited | Information & communication | 2013 |
| Easton Project Controls Planning Solutions Ltd | Administrative & support | 2025 |
| Eastwood Family Bistro Limited | Hospitality | 2026 |
| Eaton Electrical Solutions Ltd | Energy | 2020 |
| Ec&I Consulting Limited | Professional & scientific | 2022 |
| Ecus to Go Limited | Wholesale & retail | 2010 |
| EDD Limited | Real estate | 2021 |
| Edge Mentors Ltd | Professional & scientific | 2026 |
| Eileen's Traditional Fruit Market Ltd | Wholesale & retail | 2022 |
| Ej&C ENG Ltd | Professional & scientific | 2024 |
| EJP Services Limited | Construction | 2026 |
| Ekfateh Ltd | Wholesale & retail | 2020 |
| Eksukh Ltd | Wholesale & retail | 2016 |
| Elamin & Eltayeb Group Ltd | Construction | 2023 |