| ALL on Board Limited | Professional & scientific | 2001 |
| All-The-Gear Ltd | Wholesale & retail | 2018 |
| Allancia Limited | Construction | 2006 |
| Alliance Fixing Systems Limited | Wholesale & retail | 2002 |
| Alliance NDT Ltd | Professional & scientific | 2019 |
| Allo Holding Limited | Professional & scientific | 2023 |
| Almet Sheet Metal Fabrication Limited | Manufacturing | 2007 |
| Alter Inc Limited | Manufacturing | 2017 |
| Alunag Limited | Construction | 2014 |
| Alunag Manufacturing Limited | Manufacturing | 2022 |
| AM Property Development Ltd | Real estate | 2014 |
| AM67 Limited | Real estate | 2021 |
| AMA Painting & Decorating Services Limited | Construction | 2017 |
| Ambar Dhesi Events CIC | Information & communication | 2025 |
| AMC Consultants (NE) Limited | Professional & scientific | 2026 |
| AMD Marsh Logistics Ltd | Transport & logistics | 2025 |
| American Humane | | 2022 |
| AMH Workspace Ltd | Construction | 1984 |
| AMP Renewables Ltd | Professional & scientific | 2015 |
| Amsun Group Ltd | Hospitality | 2020 |
| AMX Heating Services Ltd | Construction | 2019 |
| Andrew Lamb Properties Limited | Real estate | 2025 |
| ANG Developments Limited | Construction | 2014 |
| Angel by Venus Bridal Ltd | Wholesale & retail | 2020 |
| Angels View Pet Crematorium Ltd | Other services | 2025 |
| ANS MOT Limited | Wholesale & retail | 2026 |
| Anup Health Care Services Limited | Health & social care | 2023 |
| ANV Fabrications Limited | Construction | 2020 |
| AP Estates (North East) Ltd | Construction | 2025 |
| Apantic Limited | Information & communication | 2016 |
| Apex Parcels Services Ltd | Transport & logistics | 2026 |
| Apextra C.I.C. | Education | 2012 |
| Apollo Doors Limited | Manufacturing | 1999 |
| Apollo Facility Management Ltd | Administrative & support | 2004 |
| Apollo Logistics Solutions Ltd | Transport & logistics | 2023 |
| Appleberry Designs Limited | Information & communication | 2008 |
| Applied Acoustics Ltd | Professional & scientific | 2010 |
| Aquafresh Limited | Wholesale & retail | 2005 |
| Archer and Scott Ltd | Hospitality | 2025 |
| Archer Network Solutions Ltd | Information & communication | 2011 |
| Archie's Express Desserts Ltd | Hospitality | 2024 |
| Archies Properties Ltd | Real estate | 2010 |
| Archies Stores Ltd | Wholesale & retail | 2005 |
| Architectural Base Consultancy Limited | Professional & scientific | 2014 |
| Architectural Metalworkers Limited | Manufacturing | 1997 |
| Archive Storage UK Limited | Administrative & support | 2019 |
| Ardent Plumbing & Heating Ltd | Construction | 2026 |
| ARE Aroma Limited | Hospitality | 2026 |
| Arktech (NE) Limited | Manufacturing | 2009 |
| Armah Switchgear Limited | Manufacturing | 1991 |
| Armstrong Hurst Ltd | Professional & scientific | 2025 |
| Armstrong Renewables Limited | Construction | 2014 |
| Articube UK Limited | Other services | 2012 |
| Artis Oculi Ltd | Wholesale & retail | 2023 |
| Artist Transport Ltd | Transport & logistics | 2022 |
| Artluxdeco Ltd | Manufacturing | 2025 |
| Artron Tower Pumps System Limited | Wholesale & retail | 2002 |
| AS Pipefitting Services Ltd | Construction | 2025 |
| ASC Group North East Limited | Construction | 2023 |
| ASC Properties N.E. Limited | Real estate | 2022 |
| Ascii Works Limited | Information & communication | 2011 |
| Ashburne Developments Limited | Construction | 2016 |
| Ashworth and Parker Limited | Wholesale & retail | 2009 |
| Asim (Concord) Ltd | Other services | 2018 |
| ASJ Trading Ltd | Wholesale & retail | 2016 |
| ASK 4 Glass & Glazing Contractors Ltd. | Construction | 2014 |
| ASK Ollie Ltd | Construction | 2026 |
| Askas Property Ventures Ltd | Real estate | 2023 |
| Aspen Financial Limited | Administrative & support | 2022 |
| Aspen Pensions Limited | Administrative & support | 2012 |
| Asperyco Ltd | Wholesale & retail | 2026 |
| Asra Auto Solutions Ltd | Wholesale & retail | 2025 |
| Assure Qhse Consultancy Ltd | Professional & scientific | 2026 |
| Aston Group N.E Limited | Extraterritorial | 2019 |
| Ateda Ltd | Professional & scientific | 2021 |
| Athene Properties Limited | Real estate | 2020 |
| Athlé Ltd | Manufacturing | 2025 |
| Atlantic Barbering Co. Ltd | Real estate | 2012 |
| Atlas Blinds and Shutters Limited | Construction | 2022 |
| Atlas Card Services Limited | Financial services | 2018 |
| Atlas Outdoor Living Limited | Wholesale & retail | 2026 |
| Atticus Information Technology Solutions Limited | Information & communication | 2007 |
| ATW Tree and Landscape Specialists Limited | Administrative & support | 2019 |
| Aureus Digital Ltd | Other services | 2024 |
| Auto FIX Washington Ltd | Wholesale & retail | 2014 |
| Auto Revive Car Maintenance Ltd | Wholesale & retail | 2025 |
| Automated Machine Services Limited | Professional & scientific | 2013 |
| Autoroll Investments Ltd | Professional & scientific | 2020 |
| Avalanche Vapes Ltd | Wholesale & retail | 2018 |
| Aviation Systems Consultancy Ltd | Public administration | 2007 |
| AWC (North East) Limited | Manufacturing | 1998 |
| AWL (PM) Services Limited | Construction | 2020 |
| Azis + Azis Limited | Other services | 2015 |
| Azomadiz Limited | Health & social care | 2011 |
| Aztec Print North East Limited | Manufacturing | 1997 |
| B M S Electrical Services Limited | Manufacturing | 2008 |
| B&C Woodworks Ltd | Manufacturing | 2025 |
| BAG O’ Nails Property Services Ltd | Construction | 2023 |
| Balance Trading Limited | Wholesale & retail | 2022 |
| Baller's DEN Ltd | Education | 2020 |