| 15685172 Limited | Professional & scientific | 2024 |
| 1886 Draughting Limited | Professional & scientific | 2024 |
| 333 Investments Ltd | Financial services | 2024 |
| A E L Systems Ltd | Administrative & support | 2003 |
| A FAB Limited | Manufacturing | 2017 |
| A Hudson Limited | Information & communication | 2019 |
| A-Tech Academy Ltd | Extraterritorial | 2012 |
| A-Tech Battery Handling Solutions Limited | Extraterritorial | 2013 |
| A-Tech Electronics Limited | Extraterritorial | 2013 |
| A-Tech Fabrications Limited | Manufacturing | 1994 |
| A-Tech Global Ltd | Manufacturing | 2011 |
| A-Tech Industries Ltd | Professional & scientific | 2012 |
| A-Tech Properties Limited | Real estate | 2011 |
| A-Vision Plumbing Ltd | Construction | 2022 |
| A-Vision Properties Ltd | Real estate | 2025 |
| A.D.B Management & Consultancy Ltd | Professional & scientific | 2019 |
| A.J.L. Sales Ltd | Professional & scientific | 2024 |
| A.L.M. Products Limited | Manufacturing | 1994 |
| A2B Transport and Logistics Ltd | Transport & logistics | 2025 |
| AA Mortgages and Finance Limited | Financial services | 2016 |
| AAA Appliance Care Centre Limited | Other services | 2013 |
| Abseil Repairs Ltd | Construction | 2015 |
| Absolute Plumbing and Heating NE Ltd | Other services | 2021 |
| ACA Electrical (NE) Limited | Construction | 2013 |
| Active Future Sunderland CIC | Education | 2024 |
| AD Marine Electrical Repairs Limited | Manufacturing | 2018 |
| Adicam 72 Trans Limited | Transport & logistics | 2018 |
| ADS Joinery & Building Services Limited | Construction | 2019 |
| Advance Automated Systems Limited | Manufacturing | 2003 |
| Advance Central Engineering Ltd | Manufacturing | 2020 |
| Advance Conveyor Group Ltd | Manufacturing | 2023 |
| Advance Conveyors Ltd | Professional & scientific | 2022 |
| Advance Modular Ltd | Manufacturing | 2020 |
| Advance Projects and Automation Ltd | Professional & scientific | 2020 |
| Advanced Cooling Systems Ltd | Manufacturing | 2015 |
| Aegies Associates Limited | Professional & scientific | 2006 |
| AEL Electrical Services Ltd | Construction | 2014 |
| AEL Group (Northern) Limited | Financial services | 2025 |
| AEL Limited | Extraterritorial | 1978 |
| Aesthetics With Georgia Limited | Health & social care | 2024 |
| Aesthetics With Kayleigh Ltd | Other services | 2022 |
| Aether Cirrus Limited | Information & communication | 2022 |
| Aety Ltd | Hospitality | 2022 |
| AF Engineering & Design Services Ltd | Manufacturing | 2004 |
| AF NDT Services Ltd | Professional & scientific | 2020 |
| AFB Media UK Ltd | Information & communication | 2025 |
| AG Hvac Solutions Ltd | Construction | 2025 |
| AG M&E Group Ltd | Construction | 2025 |
| AG47FM Limited | Construction | 2018 |
| Agiletek Engineering Limited | Professional & scientific | 2014 |
| AJL Utilities Limited | Energy | 2025 |
| AJX Football Club Limited | Arts & recreation | 2025 |
| Akuila Borisi Ltd | Professional & scientific | 2025 |
| Al&Rl Investments Ltd | Real estate | 2021 |
| Alan Armstrong Haulage Limited | Transport & logistics | 2016 |
| ALL Natural Supplies Limited | Wholesale & retail | 2009 |
| Allglow Ltd | Other services | 2021 |
| Altcare Associate Ltd | Health & social care | 2022 |
| Alterations by Michele Limited | Manufacturing | 2020 |
| AM Professional Mobile Valeting Services Ltd | Other services | 2017 |
| Amcore Conservatories Ltd | Construction | 2021 |
| Amelia RAY Events Ltd | Hospitality | 2023 |
| AMP Financial Services Limited | Financial services | 2022 |
| Amplified Leaders Ltd | Professional & scientific | 2024 |
| Amtech Fabrications (UK) Limited | Construction | 2006 |
| AMZ Security Ltd | Administrative & support | 2024 |
| Anchorstone Property Services Ltd | Real estate | 2026 |
| Anderson Upholstery Limited | Manufacturing | 2016 |
| Another One Bites the Dutch Ltd | Hospitality | 2024 |
| Anwen Construction Limited | Construction | 2009 |
| AP Holdings (Teesside) Limited | Financial services | 2024 |
| APB Roofing & Cladding Ltd | Construction | 2017 |
| Apex Fraction-Al Ltd | Information & communication | 2026 |
| Apex NE Construction Ltd | Construction | 2024 |
| Apex Venues Limited | Administrative & support | 2022 |
| Apmss Ltd | Professional & scientific | 2024 |
| Appleby Dodd and Russell Ltd | Other services | 2023 |
| Appletree Joinery Products Limited | Manufacturing | 1985 |
| ARC Travel Ltd | Transport & logistics | 2024 |
| Arch Clad Ltd | Construction | 2019 |
| Arch Roofing & Cladding Ltd | Construction | 2025 |
| ARF Plumbing and Heating Ltd | Construction | 2018 |
| Armiger Timber Frame Limited | Manufacturing | 2022 |
| Armitage and Wilson Furniture Ltd | Wholesale & retail | 2020 |
| Armstrong Building Services Limited | Construction | 2024 |
| Articus Insights Limited | Information & communication | 2026 |
| Ascent Control Systems Ltd | Information & communication | 2026 |
| Ascent Conveyors and Automation Ltd | Professional & scientific | 2021 |
| ASK ME HSE Ltd | Professional & scientific | 2025 |
| Asset Protection North East Ltd | Professional & scientific | 2020 |
| Atah Properties Ltd | Real estate | 2026 |
| Atrevo Systems Limited | Information & communication | 2026 |
| Ausees Energy and Environmental Solutions CIC | Professional & scientific | 2024 |
| Auto Control Touchdown Limited | Manufacturing | 2017 |
| Auto DNA Ltd | Wholesale & retail | 2023 |
| Autolab Vehicle Solutions Ltd | Wholesale & retail | 2019 |
| Automotive Chassis Products UK Limited | Manufacturing | 1988 |
| Autosafe Autocentres Ltd | Wholesale & retail | 2008 |
| Autosafe Autos Ltd | Wholesale & retail | 2025 |
| Autotech Engineering R&D UK Limited | Professional & scientific | 2012 |