| AMG Power Limited | Energy | 2024 |
| AMG Utility Solutions Ltd | Construction | 2013 |
| AMG Yorkshire (Holdings) Limited | Financial services | 2022 |
| Amgt Developments Ltd | Professional & scientific | 2025 |
| Amin's Spice Limited | Hospitality | 2016 |
| Amiragrey Ltd | Hospitality | 2018 |
| AMJ Services Limited | Professional & scientific | 2015 |
| AML Groundworks Ltd | Construction | 2019 |
| Amplify X Ltd | Professional & scientific | 2025 |
| AMR Surgical Ltd | Health & social care | 2024 |
| Amrap Education Limited | Education | 2019 |
| Amsted Developments Ltd | Other services | 2018 |
| AMZ Saddles Limited | Wholesale & retail | 2018 |
| AN Automation Limited | Information & communication | 2006 |
| AN Phat Ltd | Other services | 2025 |
| Anadysi Limited | Hospitality | 2025 |
| Analytical & Environmental Services Limited | Professional & scientific | 1989 |
| Anchor Construction Limited | Construction | 2025 |
| Ancroft Ltd | Real estate | 2022 |
| Anderson Gray Developments Ltd | Real estate | 2026 |
| Anderson Property Durham Ltd | Real estate | 2026 |
| Andersons Durham Limited | Real estate | 2022 |
| Andill House Property Company Limited | Extraterritorial | 2020 |
| Andit Consult Ltd | Education | 2025 |
| Andrea Cellerino Studio Limited | Other services | 2022 |
| Andrea's Autos Limited | Wholesale & retail | 2014 |
| Andrew Hardy Classics Ltd | Wholesale & retail | 2020 |
| Andrew Hardy Construction Ltd | Construction | 2020 |
| Andrew Johnston Financial Services Limited | Financial services | 2015 |
| Andrew White Holdings Ltd | Financial services | 2025 |
| Andy Greenwood Film & Television Services Ltd | Information & communication | 2016 |
| Andy Management (UK) Limited | Real estate | 2019 |
| ANG Accountancy Solutions Limited | Professional & scientific | 2015 |
| Angel CP Limited | Real estate | 2017 |
| Angel Durham Leisure Limited | Hospitality | 2019 |
| Angel Homes (Durham) Limited | Real estate | 2013 |
| Angel Propco (Durham) Limited | Extraterritorial | 2016 |
| Angel Rentals Limited | Real estate | 2018 |
| Angel's PH Limited | Transport & logistics | 2025 |
| Angela Waters Properties LLP | | 2016 |
| Angela Waters Rentals Ltd | Real estate | 2016 |
| Angels P&J Care Ltd | Health & social care | 2019 |
| Anglian Water Business (National) Limited | Water & waste | 1995 |
| ANI International Limited | Wholesale & retail | 2025 |
| Anneya Ltd | Hospitality | 2025 |
| ANS Hospitality Company Limited | Hospitality | 2026 |
| ANT Plant Hire Ltd | Construction | 2014 |
| Antec Mobile Limited | Information & communication | 2015 |
| Anthony Nixon Furniture Limited | Manufacturing | 2002 |
| Antigen MC Ltd | Health & social care | 2019 |
| Antnic Limited | Professional & scientific | 2006 |
| Antonie YAU Ltd | Wholesale & retail | 2025 |
| Antony G. Wharton Limited | Administrative & support | 1982 |
| Anvil Alpacas Ltd | Agriculture & fishing | 2025 |
| Anvil Property Ltd | Real estate | 2025 |
| AO Abode Limited | Real estate | 2025 |
| AO Building & Development Ltd | Construction | 2020 |
| AO Health Ltd | Wholesale & retail | 2025 |
| AP Coaching North East Limited | Arts & recreation | 2024 |
| AP Taxis Limited | Transport & logistics | 2024 |
| APA Property Developments Limited | Real estate | 2021 |
| APA Property Maintenance Limited | Real estate | 2020 |
| APB Mortgages Ltd | Professional & scientific | 2017 |
| APB Pro Ltd | Construction | 2025 |
| Apex Light Photography Limited | Professional & scientific | 2025 |
| API Limited | Real estate | 2004 |
| APL Event Limited | Administrative & support | 2012 |
| Apollo International Services Ltd | Construction | 2024 |
| Apollo Leeds Ltd | Arts & recreation | 2026 |
| Apollo TC Ltd | Arts & recreation | 2024 |
| App Factory Consultants Ltd | Information & communication | 2020 |
| Apple Farm Ltd | Real estate | 2021 |
| Appleby Property Limited | Real estate | 2024 |
| Applification Limited | Information & communication | 2009 |
| Aqua Advice Ltd | Professional & scientific | 2022 |
| AR Building Contractors (North East) Limited | Construction | 2017 |
| Ar-She Ltd | Wholesale & retail | 2023 |
| Araz Global Ltd | Wholesale & retail | 2025 |
| Arborline Tree Services Ltd | Administrative & support | 2023 |
| Arbour House Farm Medical and Agricultural Ltd | Agriculture & fishing | 2021 |
| ARC Training (NE) Ltd | Wholesale & retail | 2025 |
| Arcanum Group Ltd | Professional & scientific | 2022 |
| Arch Civils Limited | Construction | 2025 |
| Archie Care Limited | Health & social care | 2012 |
| Archtevo Estates Limited | Construction | 2019 |
| Arclight Marketing and Media Limited | Professional & scientific | 2012 |
| ARD Property Investments NE Limited | Real estate | 2019 |
| Arden Security Group Ltd | Administrative & support | 2025 |
| Areesha Foods Ltd | Hospitality | 2024 |
| Aressa Ltd | Wholesale & retail | 2023 |
| Aria AMI Limited | Real estate | 2025 |
| Ariarad Limited | Health & social care | 2023 |
| ARK Services (NE) LLP | | 2023 |
| Arkley Holdings Limited | Professional & scientific | 2021 |
| Arktek Heating Services Limited | Wholesale & retail | 2016 |
| ARM Pipetek Ltd | Construction | 2013 |
| Armature Labs Limited | Information & communication | 2026 |
| Armford Legal (NE) Ltd | Professional & scientific | 2015 |
| Armoured Alarms Limited | Administrative & support | 2018 |
| Arora Consultancy Services Limited | Professional & scientific | 2016 |