| AH Consultancy NE Ltd | Professional & scientific | 2019 |
| AH Property NE Ltd | Real estate | 2021 |
| AH Tech Services Ltd | Professional & scientific | 2024 |
| Ahmed Catering Ltd | Hospitality | 2021 |
| AI Help Squad Ltd | Professional & scientific | 2025 |
| AIG Electrical Limited | Construction | 2016 |
| Aigostar International Limited | Wholesale & retail | 2015 |
| AIM Complete Solutions Ltd | Professional & scientific | 2026 |
| Aimfutura Ltd | Professional & scientific | 2023 |
| Aiza Kebabs and Grill Ltd | Hospitality | 2025 |
| AJB Ltd | Wholesale & retail | 2018 |
| AJC Financial Limited | Professional & scientific | 2012 |
| AJH Electrical Solutions Ltd | Administrative & support | 2017 |
| AJH Rigging Limited | Professional & scientific | 2023 |
| AJL Wind Renewables Ltd | Construction | 2025 |
| AJM Electrical Testing Services Limited | Manufacturing | 2005 |
| AJS Fabrication Services Ltd | Construction | 2020 |
| AK & SAM Ltd | Health & social care | 2024 |
| AK Lettings & Property Management Ltd | Real estate | 2025 |
| AK Social Ltd | Arts & recreation | 2021 |
| AKB Interiors Group Ltd | Construction | 2026 |
| AKI Supermarket Ltd | Wholesale & retail | 2025 |
| AKM Northeast Ltd | Real estate | 2022 |
| AKQ Properties Limited | Real estate | 2025 |
| Aktiv Performance Limited | Wholesale & retail | 2019 |
| Alan MAC Mech Ltd | Professional & scientific | 2026 |
| Albion Electrical Limited | Construction | 2007 |
| Albion Gaul Limited | Education | 2009 |
| Album Group Limited | Information & communication | 2024 |
| ALC Building Co Ltd | Construction | 2021 |
| Alchino's Pizza Ltd | Hospitality | 2022 |
| Aldar Property Limited | Real estate | 2014 |
| Alexander's Interiors Limited | Manufacturing | 2017 |
| Alfro Ltd | Construction | 2012 |
| ALH Hartlepool Limited | Construction | 2024 |
| Alice House Trading Limited | Health & social care | 2010 |
| Alice Widdows Limited | Other services | 2014 |
| ALK Inspections Ltd | Professional & scientific | 2024 |
| Alkane Limited | Real estate | 1999 |
| Alkebulan Homes & Villas Ltd | Hospitality | 2025 |
| Alkena Homes Ltd | Real estate | 2026 |
| ALL Programming Ltd | Information & communication | 2025 |
| ALL Things (NE) Ltd | Extraterritorial | 2022 |
| Allen Fabrications (N.E.) Ltd | Manufacturing | 2017 |
| Allistone Property Development Ltd | Construction | 2025 |
| Allium Housing CIC | Real estate | 2022 |
| Almn Fixers Limited | Construction | 2025 |
| Alpha Paints Hartlepool Ltd | Wholesale & retail | 2017 |
| Alpha Stone Experts Ltd | Construction | 2020 |
| Alpha Visionary Logistics Ltd | Wholesale & retail | 2024 |
| Alphadeltawhiskey Access Ltd | Professional & scientific | 2026 |
| Altitude Creator Network Limited | Professional & scientific | 2025 |
| Altitude Weldtech Services Ltd | Manufacturing | 2014 |
| Alton Property Sales Ltd | Financial services | 2019 |
| Altonlord Limited | Water & waste | 1985 |
| AM Construction Solutions Ltd | Construction | 2019 |
| AM Mortgages (NE) Limited | Financial services | 2017 |
| Am&J Ltd | Hospitality | 2024 |
| AM5 Properties Limited | Real estate | 2025 |
| AMA Business Services Limited | Professional & scientific | 2009 |
| AMB Brickwork Ltd | Construction | 2018 |
| AMB Piping Services Ltd | Professional & scientific | 2021 |
| Ambience Aroma Ltd | Other services | 2025 |
| Amble and Sonder Limited | Professional & scientific | 2022 |
| Amble Developments Limited | Real estate | 2006 |
| Amen Plant Limited | Construction | 2012 |
| Ames Services Limited | Construction | 2018 |
| AMG Private Ltd | Wholesale & retail | 2020 |
| AMJ Solutions Limited | Construction | 2025 |
| Amore Pizzeria UK Limited | Hospitality | 2019 |
| Amplify Leadership Ltd | Professional & scientific | 2024 |
| AMR Fire Risk Assessments Ltd | Public administration | 2025 |
| Amsrad Limited | Health & social care | 2025 |
| AMW Professional Ltd | Professional & scientific | 2019 |
| ANA Lifestyle Express Ltd | Wholesale & retail | 2021 |
| Anas Northeast Ltd | Other services | 2025 |
| Anchor & Coal Ltd | Hospitality | 2024 |
| Anchor Home Refurbs Ltd | Construction | 2023 |
| Andes Trading Limited | Wholesale & retail | 2007 |
| Andleeb Traders Ltd | Other services | 2026 |
| Andon Ltd | Real estate | 2011 |
| Andreac Ltd | Health & social care | 2023 |
| Andrew Harker Groundworks and Landscaping Ltd | Administrative & support | 2007 |
| Andy Smiles MOT & Repair Limited | Wholesale & retail | 2024 |
| Andy.D.Electrical Ltd | Construction | 2022 |
| Andyshoots Ltd | Information & communication | 2026 |
| Angel Apartments Ltd | Households | 2021 |
| Angel ARK Ltd | Education | 2023 |
| Angel of the North Property Investment Ltd | Financial services | 2017 |
| Angling Leisure Ltd | Agriculture & fishing | 2022 |
| ANN Cordey Lettings Limited | Real estate | 2026 |
| Anna Campbell Hairdressing Limited | Other services | 2016 |
| Anthony Pugh Ltd | Construction | 2022 |
| Anthonymelendrez Ltd | Professional & scientific | 2022 |
| Antinick Ltd | Transport & logistics | 2012 |
| ANU Shyni Foods Ltd | Hospitality | 2024 |
| AO Solutions Ltd | Transport & logistics | 2025 |
| AO Transport Ltd | Transport & logistics | 2025 |
| AP Audio Ltd | Administrative & support | 2025 |
| AP Sonography Limited | Health & social care | 2014 |