| Ager Building Services Ltd | Construction | 2022 |
| Ageuk County Durham | Extraterritorial | 2010 |
| Ageuk County Durham Trading Limited | Extraterritorial | 2010 |
| Agilitti Recruitment Solutions Ltd | Administrative & support | 2019 |
| AGL (NE) Ltd | Financial services | 2022 |
| AGM Houses Ltd | Real estate | 2020 |
| Agpc Sports Solutions Limited | Information & communication | 2026 |
| Agras Ventures Ltd | Wholesale & retail | 2025 |
| Agricultural Polymers International Limited | Agriculture & fishing | 1992 |
| Agritrack Ltd | Manufacturing | 2024 |
| Agshin Aslanov Ltd | Wholesale & retail | 2025 |
| AGU (NE) Limited | Energy | 2026 |
| Agunify Ltd | Wholesale & retail | 2025 |
| AH2 Property Ltd | Real estate | 2023 |
| Ahmetoglu Ltd | Wholesale & retail | 2025 |
| Ahsen London Ltd | Wholesale & retail | 2025 |
| AHT Construction NE Ltd | Construction | 2023 |
| AI Property Holdings Limited | Real estate | 2021 |
| Aidan Gardens Management Limited | Other services | 2017 |
| Aimee Financial Ltd | Financial services | 2019 |
| Ainsdale Investments Limited | Real estate | 2025 |
| Aipex Robotics Limited | Manufacturing | 2025 |
| Air EO Ltd | Manufacturing | 2018 |
| Air Integrity Solutions Limited | Professional & scientific | 2025 |
| Airborne Access Limited | Construction | 2015 |
| Airstreamly Retro Ltd | Hospitality | 2019 |
| Airwer Limited | Information & communication | 2001 |
| Aisle Avenue Bridal Limited | Wholesale & retail | 2024 |
| Aisling Limited | Professional & scientific | 2021 |
| Aiza Indian Limited | Hospitality | 2024 |
| AJ Automedics Ltd | Wholesale & retail | 2016 |
| AJ Site Services Limited | Professional & scientific | 2025 |
| AJ Wilson Plumbing & Heating Ltd | Energy | 2006 |
| Ajeb Investment Limited | Hospitality | 2020 |
| AJH Automotive Ltd | Wholesale & retail | 2023 |
| Ajpp Management Ltd | Professional & scientific | 2023 |
| AJR Durham Limited | Hospitality | 2021 |
| AJS Associates Limited | Wholesale & retail | 2000 |
| Ajsd Holdings Limited | Financial services | 2022 |
| AJW Consultancy NE Ltd | Professional & scientific | 2026 |
| AJW Wind Services Ltd | Construction | 2026 |
| AK SOL Ltd | Information & communication | 2008 |
| AKA Barbers NE Ltd | Other services | 2026 |
| Akan Ltd | Wholesale & retail | 2026 |
| Akarsu Turkish Restaurant and Grill Limited | Hospitality | 2016 |
| Akkaya Enterprises Limited | Real estate | 2026 |
| Akupara Ltd | Information & communication | 2024 |
| AL Day Leisure Ltd | Hospitality | 2024 |
| AL Hungary Ltd | Wholesale & retail | 2025 |
| AL Jointing Services Ltd | Construction | 2021 |
| AL Solutionz Ltd | Wholesale & retail | 2017 |
| Alagoz International Ltd | Wholesale & retail | 2024 |
| Alan Bell Caravan & Motorhomes Limited | Wholesale & retail | 2013 |
| ALB ENG Fruits Ltd | Wholesale & retail | 2025 |
| ALB Italia 1 Limited | Hospitality | 2023 |
| ALB Italia Ltd | Hospitality | 2022 |
| Albert & Charlie’S Mobile Bars Ltd | Hospitality | 2020 |
| Aldus Sourcing Limited | Real estate | 2026 |
| Alex Gore AG Limited | Information & communication | 2025 |
| Alex Lowther Ltd | Health & social care | 2019 |
| Alfresko Ltd | Construction | 2020 |
| ALI Ghobadi Limited | Information & communication | 2023 |
| ALI ORR Limited | Health & social care | 2020 |
| Alice Elizabeth Ltd | Wholesale & retail | 2019 |
| Alington House Community Association | Other services | 2005 |
| Aliz Trade Ltd | Wholesale & retail | 2025 |
| ALL New Design Ltd | Wholesale & retail | 2017 |
| ALL Sparks Electrical Services Ltd | Construction | 2014 |
| Allbayz Limited | Information & communication | 2024 |
| Alliance Catering Ltd | Hospitality | 2025 |
| Allied Domain Limited | Real estate | 2003 |
| Allotrope Scientific Ltd | Manufacturing | 2021 |
| Almond Flex Limited | Health & social care | 2023 |
| Alovaco Ltd. | Wholesale & retail | 2012 |
| ALP Poachers Limited | Hospitality | 2024 |
| ALP Tuna Limited | Wholesale & retail | 2025 |
| Alpa Solutions Ltd | Professional & scientific | 2025 |
| Alpha Events and Stadium Management Ltd | Public administration | 2017 |
| Alpha Security Training Limited | Administrative & support | 2020 |
| Alpinece Ltd | Wholesale & retail | 2024 |
| Alterprivso Ltd | Public administration | 2025 |
| Altin Properties Ltd | Households | 2019 |
| Altior Holdings Limited | Financial services | 2018 |
| Altogether Greener Ltd | Administrative & support | 2010 |
| Alvin Ltd | Arts & recreation | 2025 |
| Alviss Analysts Ltd | Professional & scientific | 2021 |
| AM Housing & GRT Consultancy Limited | Professional & scientific | 2026 |
| AM N/East Ltd | Real estate | 2025 |
| Amaani Restaurant Limited | Hospitality | 2025 |
| Amac Properties (NE) Ltd | Real estate | 2024 |
| Amanni Ltd | Extraterritorial | 2021 |
| Amaze ME Interiors Ltd | Professional & scientific | 2018 |
| Amazing Antiques ETC. Ltd. | Wholesale & retail | 2019 |
| Amazing Packaging ETC. Ltd. | Wholesale & retail | 2020 |
| Amber Overage Limited | Financial services | 2018 |
| AMBITION4FOOT Ltd | Public administration | 2022 |
| Ambitious Motion Pictures Limited | Information & communication | 2008 |
| Ameera's 2010 Ltd | Hospitality | 2025 |
| Amerikana LLP | | 2014 |
| AMG Energy North East Limited | Energy | 2024 |