| Digital Consultants Limited | Information & communication | 2018 |
| Digital Edge Limited | Information & communication | 2002 |
| Digital Jobs Limited | Administrative & support | 2024 |
| Digital Opportunities Ltd | Information & communication | 2025 |
| Digital Root Marketing Limited | Professional & scientific | 2026 |
| Digitatnet Ltd | Information & communication | 2022 |
| Dillon and SON Plant Hire Limited | Administrative & support | 2024 |
| Dillon Morse Football Limited | Arts & recreation | 2022 |
| Dillon Sales and Lettings Ltd | Real estate | 2022 |
| Dilmac Group Ltd | Wholesale & retail | 2024 |
| Dinkys Boutique Limited | Wholesale & retail | 2017 |
| Direct Car Parts Limited | Wholesale & retail | 2005 |
| Direct Store Ltd | Wholesale & retail | 2025 |
| Direct Waste Solutions Ltd | Water & waste | 2025 |
| Disabled Student Support Limited | Education | 2024 |
| Discovery Design Limited | Information & communication | 1998 |
| Ditmas Company Limited | Hospitality | 2024 |
| Dixflops Protection Ltd | Financial services | 2020 |
| Dizzy Duck Limited | Wholesale & retail | 2007 |
| DJ Birtley Limited | Administrative & support | 2021 |
| DJ Heaton Limited | Administrative & support | 2021 |
| DJ Ryhope Limited | Real estate | 2016 |
| DJL Groundworks Limited | Construction | 2022 |
| DJS Heating & Renewables Ltd | Construction | 2021 |
| DK Construction Services (NE) Ltd | Construction | 2015 |
| DK Logistic Services Limited | Transport & logistics | 2015 |
| Dkct Lettings Ltd | Real estate | 2022 |
| DKR Medical Services Limited | Health & social care | 2014 |
| DKS Diving Ltd | Mining & quarrying | 2024 |
| DLM Electrical Services Ltd | Construction | 2026 |
| DLT Dental Limited | Health & social care | 2012 |
| DM Sports and Swedish Massage Specialist Ltd | Health & social care | 2025 |
| DMA 2021 Limited | Other services | 2021 |
| DMC 4 Durham CIC | Arts & recreation | 2019 |
| DMG Food Labelling Limited | Hospitality | 2020 |
| DMO Ltd | Administrative & support | 2022 |
| DMP Arena Trading Limited | Arts & recreation | 2013 |
| DMR Projects Limited | Construction | 2018 |
| DN24 Limited | Real estate | 2022 |
| Dobro IT Services Ltd | Information & communication | 2023 |
| DOC Black INK Ltd | Other services | 2011 |
| DOC Black Ltd | Wholesale & retail | 2007 |
| DOC Martin Northern Limited | Health & social care | 2025 |
| DOC Property Management Limited | Real estate | 2020 |
| Docdrawer Limited | Information & communication | 2020 |
| Dodds Groundworks & Reinstatement Ltd | Construction | 2023 |
| Dokur Ltd | Wholesale & retail | 2023 |
| DOKUR4 Ltd | Wholesale & retail | 2024 |
| Dolan's Paving & Building Ltd | Construction | 2019 |
| Dolce Vella Ltd | Wholesale & retail | 2025 |
| Dolphin Financial Services Limited | Financial services | 2020 |
| Dolphin Tooling Limited | Wholesale & retail | 2006 |
| DOM Lydon Coaching Ltd | Administrative & support | 2021 |
| Dombridge Transport Ltd | Transport & logistics | 2024 |
| Dommeans Interiors Limited | Construction | 2025 |
| Dorchester Group Holdings Ltd | Financial services | 2025 |
| Dorchester Group Investments Ltd | Financial services | 2025 |
| Dorchester Group Real Estate Ltd | Financial services | 2025 |
| Dorchester Group Services Ltd | Financial services | 2025 |
| Dotties Deli Ltd | Hospitality | 2025 |
| Double Brass Limited | Hospitality | 2024 |
| Double Strand Ltd | Professional & scientific | 2023 |
| Doulton Court Management Company Limited | Real estate | 2003 |
| Dove Design Ltd | Information & communication | 2023 |
| Dove Tale Joint Limited | Arts & recreation | 2015 |
| Downton Interiors Limited | Wholesale & retail | 2019 |
| DP Educational Services Ltd | Education | 2018 |
| DP Plant Hire Limited | Administrative & support | 1997 |
| DPM Groundworks NE Ltd | Construction | 2023 |
| Dpmj Energy Limited | Professional & scientific | 2017 |
| DQC Equine Limited | Agriculture & fishing | 2022 |
| DR BEN Marram Psychology Limited | Health & social care | 2020 |
| DR Xcalibur Autoworks Limited | Wholesale & retail | 2025 |
| DR. D&D Aesthetics Ltd | Other services | 2022 |
| DR. Lucy Turnbull Ltd | Health & social care | 2022 |
| Dr.Sahand Aesthetic Ltd | Other services | 2025 |
| Dracup Financial Services Limited | Financial services | 2017 |
| Dragonchild Limited | Other services | 2013 |
| DRC Consulting (CDM) Limited | Professional & scientific | 2020 |
| DRC Consulting (NE) Limited | Professional & scientific | 2017 |
| DRD Holdings Limited | Financial services | 2019 |
| Dream Car Warehouse Ltd | Wholesale & retail | 2024 |
| Dream Dolls Ltd | Other services | 2023 |
| DRESS2SELL Limited | Professional & scientific | 2026 |
| Dresser Property Investments Ltd | Real estate | 2024 |
| Dresser Property Ltd | Real estate | 2019 |
| DRH Projects Ltd | Construction | 2022 |
| Drive Safely Ltd | Real estate | 2019 |
| Driveways North East Limited | Construction | 2024 |
| Drknowd Limited | Professional & scientific | 2023 |
| Dromonby Country Parks Limited | Hospitality | 2019 |
| Dropnshop Trade Ltd | Wholesale & retail | 2025 |
| Dryburn Properties Ltd | Real estate | 2026 |
| DS4 Hospitality Ltd | Hospitality | 2025 |
| DSC Coachworks Ltd | Wholesale & retail | 2010 |
| DSD Investment (NE) Ltd | Real estate | 2021 |
| DSG 2000 Ltd | Construction | 2020 |
| DSH Bowburn Limited | Administrative & support | 2022 |
| DSR Leisure Ltd | Hospitality | 2018 |
| Dstead Offshore Ltd | Construction | 2019 |