| Addquest Limited | Professional & scientific | 1989 |
| Adegboyega Bello Family Holdings Ltd | Real estate | 2019 |
| Adegboyega Bello Family Partnership LLP | | 2019 |
| Adelola Ltd | Health & social care | 2020 |
| Admiralty Developments Ltd | Construction | 2018 |
| Admiralty Properties Ltd | Real estate | 2021 |
| ADR Housing Solutions Ltd | Real estate | 2026 |
| Advanced Clutch Ltd | Wholesale & retail | 2025 |
| Advantage Property Limited | Real estate | 2025 |
| Adyanda Ltd | Transport & logistics | 2021 |
| AEB Health Limited | Health & social care | 2017 |
| Aesthetic Surgery Limited | Health & social care | 2011 |
| AET Developments Ltd | Health & social care | 2021 |
| AFM Billingham Limited | Wholesale & retail | 2026 |
| After Sport Ltd | Real estate | 2024 |
| Agola Holdings Limited | Real estate | 2020 |
| Agola Partnership LLP | | 2020 |
| Agudom Limited Liability Partnership | | 2018 |
| Ahdinproperty Limited | Real estate | 2025 |
| Ahimiha Limited | Wholesale & retail | 2025 |
| Ahmad Family Holdings Ltd | Real estate | 2019 |
| Ahmad Family Partnership LLP | | 2019 |
| Airman Engineering Services Limited | Extraterritorial | 2001 |
| AIT Mitra Properties Limited | Households | 2025 |
| AJ Books Limited | Information & communication | 2024 |
| Ajaib Family Partnership LLP | | 2018 |
| AJF Engineering Limited | Manufacturing | 2018 |
| AJL Engineering Ltd | Mining & quarrying | 2026 |
| AJT Commercial Limited | Professional & scientific | 2013 |
| AK Access Limited | Professional & scientific | 2019 |
| AKA Private Ltd | Health & social care | 2023 |
| Akira Aligners and Whitening Ltd | Manufacturing | 2024 |
| Akna LLP | | 2019 |
| AKQ Telecomunications UK Limited | Administrative & support | 2023 |
| Akram Investment Group Ltd | Real estate | 2024 |
| Al-Ali Investments & Developments Ltd | Construction | 2021 |
| Al-Ali Property Group Ltd | Real estate | 2019 |
| Al-Faham Estates LLP | | 2025 |
| Al-Madina Almonawara Limited | Health & social care | 2025 |
| Al-Noor Medical Ltd | Health & social care | 2022 |
| Alali Developments Ltd | Real estate | 2024 |
| Alali Holdings Ltd | Real estate | 2024 |
| Alanna Property Portfolio Limited | Real estate | 2021 |
| ALD Car and Commercial Ltd | Wholesale & retail | 2022 |
| Aldridge Family Holdings Ltd | Real estate | 2020 |
| Aldridge Family Partnership LLP | | 2020 |
| Aleph Health Ltd | Health & social care | 2023 |
| Alex Sexton Ltd | Professional & scientific | 2024 |
| Alexander Sinclair (N.E.) Limited | Construction | 1989 |
| Alf's Coffee Shop Ltd | Hospitality | 2018 |
| Alfie Fawcett Jones Ltd | Transport & logistics | 2026 |
| ALH Clinical Ltd | Health & social care | 2026 |
| Allacien Limited | Professional & scientific | 2003 |
| Allenthorne Properties Limited | Real estate | 2024 |
| Allison Barra Ltd | Hospitality | 2021 |
| Allison Plant Services Limited | Construction | 2016 |
| Alpha Voice Communications Ltd | Other services | 2010 |
| Altarra Healing Limited | Health & social care | 2023 |
| Altarra Limited | Administrative & support | 2015 |
| Altman Family Partnership LLP | | 2019 |
| AM Access Inspections Ltd | Construction | 2015 |
| AM Cabling Limited | Construction | 2021 |
| AM Engineering Ltd | Professional & scientific | 2009 |
| AM Global Consultants Limited | Administrative & support | 2014 |
| AM Recruitment Europe Limited | Administrative & support | 2025 |
| AM Training (North East) Ltd | Education | 2022 |
| AM88 Investments Limited | Financial services | 2025 |
| AM88 Locum Ltd | Health & social care | 2015 |
| Amaryllis House Ltd | Administrative & support | 2013 |
| Amaya Investments NE Ltd | Real estate | 2022 |
| Ambro Transport & Recovery Ltd | Wholesale & retail | 2017 |
| Amelia's Bakery Limited | Hospitality | 2024 |
| Americano Coffee Ltd | Manufacturing | 2025 |
| Amerigo Project Services Limited | Administrative & support | 2011 |
| Amerineni Limited | Health & social care | 2013 |
| AMG Partnership LLP | | 2023 |
| Amigos 3 Limited | Real estate | 2012 |
| AN Medical Ltd | Health & social care | 2021 |
| Ancam Ltd | Arts & recreation | 2024 |
| Andrew Nicholson Consultancy Limited | Arts & recreation | 2010 |
| Andrew Simmons Limited | Information & communication | 2025 |
| Andy Lowe Plumbing Services Limited | Manufacturing | 2009 |
| Angelship Ltd | Real estate | 2019 |
| Anglo Care Management Ltd | Health & social care | 2024 |
| Anita Wheelhouse Consultancy Ltd | Health & social care | 2022 |
| Anna Doran Health Ltd | Health & social care | 2025 |
| Anna Future Limited | Construction | 2023 |
| Anna Partnership LLP | | 2018 |
| Anna Property Limited | Real estate | 2018 |
| Anth Leyshon Site Services Ltd | Manufacturing | 2022 |
| Antonia Edward Hair Design Limited | Other services | 2002 |
| Anzu Family Medical Ltd | Health & social care | 2022 |
| AP Watson Partnership LLP | | 2021 |
| Apex Endeavours Ltd | Real estate | 2021 |
| Apex Teaching and Learning Ltd | Education | 2026 |
| Apexway Ltd | Real estate | 2022 |
| APM Project Management Solutions Ltd | Professional & scientific | 2014 |
| Apmvc Trading Ltd | Wholesale & retail | 2024 |
| Apollo Reward Solutions Limited | Professional & scientific | 2012 |
| Appleton Associates (UK) Limited | Professional & scientific | 2017 |