| Ashfield Court, LOW Fell, Management Limited | Households | 2019 |
| Ashley H Hair Design Ltd | Other services | 2025 |
| Ashtal Limited | Health & social care | 2021 |
| ASM Renewables Ltd | Professional & scientific | 2026 |
| Aspen Homes Management Limited | Real estate | 2022 |
| Aspire Solutions Group Limited | Financial services | 2018 |
| Aspire Solutions Holdings Limited | Information & communication | 2020 |
| Aspire Technology Alliance Limited | Financial services | 2025 |
| Aspire Technology Enterprise Limited | Information & communication | 2021 |
| Aspire Technology Holdings Limited | Financial services | 2025 |
| Aspire Technology Investment Limited | Information & communication | 2022 |
| Aspire Technology Operations Limited | Financial services | 2025 |
| Aspire Technology Solutions Commercial Ltd | Information & communication | 2017 |
| Aspire Technology Solutions Ltd | Information & communication | 2006 |
| Assessor Consulting Ltd | Professional & scientific | 2017 |
| Asset Integrity Support Ltd | Professional & scientific | 2019 |
| Assetsound Limited | Construction | 1988 |
| Assure Survey Limited | Professional & scientific | 2006 |
| Assured Support NE Ltd | Administrative & support | 2025 |
| Astley Freehold Ltd | Extraterritorial | 2015 |
| Astley Investments Ltd | Extraterritorial | 2015 |
| Astley Seaton Delaval Ltd | Extraterritorial | 2015 |
| Astley Signs Limited | Manufacturing | 1990 |
| Aston Construction (NE) Ltd | Construction | 2019 |
| Aston Developments NE Ltd | Construction | 2025 |
| Aston Holdings NE Ltd | Financial services | 2025 |
| Aston Parts 24-7 Ltd | Wholesale & retail | 2016 |
| Aston Walker Developments Limited | Construction | 2018 |
| Aston Workshop Restorations Limited | Wholesale & retail | 2024 |
| Astonmoore Limited | Other services | 2020 |
| Astonwalker Holdings Limited | Construction | 2021 |
| Astrad Properties Ltd | Real estate | 2022 |
| Astraea Health Limited | Manufacturing | 2026 |
| Astro Ventures C.I.C. | Education | 2013 |
| Astute Interior Design Limited | Wholesale & retail | 2023 |
| AT Euro Ltd | Health & social care | 2024 |
| AT Home in the Community Limited | Health & social care | 1990 |
| Atb.N Ltd | Real estate | 2025 |
| Atelis Ltd | Professional & scientific | 2024 |
| Ateres | Education | 2011 |
| Athena Newcastle Limited | Administrative & support | 2014 |
| Athos Commercial Finance Limited | Financial services | 2026 |
| Atif Bilal Consultancy Limited | Professional & scientific | 2013 |
| Atkinson Technology Limited | Information & communication | 2015 |
| ATL Precision Engineering Ltd | Manufacturing | 2015 |
| Atlantic Real Estate Investments Limited | Real estate | 2025 |
| Atlas GAS NE Ltd | Construction | 2026 |
| Atlas Global Travel Limited | Administrative & support | 2025 |
| Atlas Introducers Ltd | | 2010 |
| Atlas North East Business Support Ltd | Arts & recreation | 2021 |
| Atlas North East CIC | Arts & recreation | 2012 |
| Atlas Tunnelling Ltd | Wholesale & retail | 2024 |
| Atmath Ltd | Information & communication | 2026 |
| Atolia & Atolia Limited | Wholesale & retail | 2022 |
| Atom International Limited | Professional & scientific | 2015 |
| Atom Properties North East Ltd | Real estate | 2021 |
| Attest Inspection Limited | Professional & scientific | 2012 |
| AU& Co Services Limited | Professional & scientific | 2014 |
| AU1908 Ltd | Professional & scientific | 2021 |
| Audio Republic (North) Ltd | Wholesale & retail | 2022 |
| Audio Republic Limited | Wholesale & retail | 2002 |
| Augmentum Cnot Technology Limited | Financial services | 2019 |
| Augnet Ltd. | Information & communication | 2018 |
| Auralis Design Studio Ltd | Professional & scientific | 2026 |
| Aurum Retail Partners Ltd | Wholesale & retail | 2026 |
| Auto & Marine Composites Ltd | Manufacturing | 2011 |
| Auto DOC Service Ltd | Wholesale & retail | 2026 |
| Auto Enrolment and Payroll Services Limited | Professional & scientific | 2014 |
| Auto Express (Transport) Ltd | Transport & logistics | 2003 |
| Auto Solutions & MOT Ltd | Wholesale & retail | 2025 |
| AUTO617 Limited | Manufacturing | 2025 |
| Autocalls Ltd | Extraterritorial | 2026 |
| Autoclock Holdings Limited | Financial services | 2010 |
| Automotive Glazing Fleet UK Ltd | Wholesale & retail | 2024 |
| Autoshield Protection Limited | Wholesale & retail | 2007 |
| Autosites (Europe) Limited | Professional & scientific | 2004 |
| Autum Breez Limited | Information & communication | 2021 |
| Autum Leaf Solutions Limited | Professional & scientific | 2019 |
| Autumn Ford Management Company Limited | Households | 2024 |
| Autumn Ridge Ltd | Real estate | 2018 |
| AV Orthopaedics Ltd | Health & social care | 2023 |
| AVA Enterprises Ltd | Households | 2025 |
| Avalos Services Ltd | Real estate | 2025 |
| Avania Haus Limited | Health & social care | 2025 |
| Avatarshield AI Limited | Information & communication | 2026 |
| Avenora London Ltd | Manufacturing | 2026 |
| Aventurine Climate Dargavel Ltd | Other services | 2025 |
| Aventurine Climate Ltd | Other services | 2025 |
| Aventurine Training Limited | Education | 2018 |
| Avenue Holdings (NE) Ltd | Real estate | 2021 |
| Avichay Ltd | Real estate | 2026 |
| Avid Technology Group Limited | Financial services | 2009 |
| Avid Technology Limited | Manufacturing | 2003 |
| Aviyon Estates Ltd | Real estate | 2018 |
| Aviyon Finance Ltd | Financial services | 2020 |
| Avondale Metals Ltd | Wholesale & retail | 2016 |
| Avreichim Gateshead | Other services | 2017 |
| Avyadavs Ltd | Hospitality | 2026 |
| AW Media Recruitment Limited | Administrative & support | 2018 |
| Awc.Gan Ltd | Health & social care | 2022 |