| Atlas Travel Middlesbrough Ltd | Transport & logistics | 2024 |
| ATM Ayurveda & Holistic Cure Ltd. | Health & social care | 2014 |
| Atmcloughservices Limited | Construction | 2026 |
| Atmit Ltd | Manufacturing | 2023 |
| Atom Inspections Ltd | Professional & scientific | 2020 |
| Atratus Ltd | Wholesale & retail | 2022 |
| Atrueman Rigging Services Limited | Construction | 2026 |
| Atum Ventures Ltd | Information & communication | 2013 |
| AU Inspection Services Limited | Professional & scientific | 2018 |
| Auckland Business Park Ltd | Real estate | 2024 |
| Auld Bistro Eyemouth Ltd | Hospitality | 2026 |
| Aurasell Limited | Wholesale & retail | 2026 |
| Aurel Solutions Ltd | Administrative & support | 2021 |
| Aurovia London Ltd | Wholesale & retail | 2026 |
| Austin Cardiology Services Ltd | Health & social care | 2020 |
| Austin Rose Maritime Limited | Transport & logistics | 2024 |
| Auteestic CIC | Education | 2026 |
| Auto FIX (NE) Ltd | Wholesale & retail | 2025 |
| Auto Recovery Services NE Limited | Transport & logistics | 2021 |
| Auto Smart Limited | Wholesale & retail | 2024 |
| Auto Spares N.E Ltd | Wholesale & retail | 2024 |
| Auto Tyres & Body Work Ltd | Wholesale & retail | 2026 |
| Autofixmate Ltd | Wholesale & retail | 2025 |
| Autoleisure NE Ltd | Wholesale & retail | 2026 |
| Automation Talent Recruitment Ltd | Administrative & support | 2019 |
| Automotive Creation Limited | Wholesale & retail | 2011 |
| Automotive Independent Limited | Professional & scientific | 1999 |
| Autotech Centre Ltd | Wholesale & retail | 2026 |
| Auxilium Finance Limited | Professional & scientific | 2021 |
| Auxilium Holdings Ltd | Professional & scientific | 2022 |
| AV Merchants Ltd | Wholesale & retail | 2026 |
| Avenium Engineering Ltd | Manufacturing | 2015 |
| Aventra Services Ltd | Information & communication | 2025 |
| Aventura Services (2014) Limited | Information & communication | 2014 |
| Aventus Houses Ltd | Hospitality | 2023 |
| Avenue Hospitality Limited | Hospitality | 2026 |
| AVL Trade Sales LLP | | 2013 |
| AVL Vehicle Hire Ltd | Administrative & support | 2021 |
| AVM Fish N Chips Ltd | Hospitality | 2021 |
| AW Bond Limited | Professional & scientific | 2021 |
| AW Bytes Limited | Information & communication | 2024 |
| AW Developments North East Ltd | Construction | 2019 |
| AW Group Middlesbrough Ltd | Hospitality | 2025 |
| AW Lifting (NE) Ltd | Professional & scientific | 2019 |
| AW Wind Services Ltd | Construction | 2017 |
| Awesome Concepts Ltd | Administrative & support | 2023 |
| Awesome Studio Limited | Information & communication | 2019 |
| AWG Civil Engineering Limited | Construction | 2010 |
| Awis Enterprise Limited | Transport & logistics | 2019 |
| AWM Alarms Limited | Administrative & support | 2003 |
| Awovex Ltd | Wholesale & retail | 2026 |
| AWP Consultants Ltd | Professional & scientific | 2025 |
| AWS EHV Services Ltd | Professional & scientific | 2022 |
| AX Lords Glazing Ltd | Construction | 2024 |
| Axilerator Ltd. | Professional & scientific | 2022 |
| Axiocom Ltd | Wholesale & retail | 2025 |
| Axiom Events Group Ltd | Real estate | 2022 |
| Axiom Events Limited | Arts & recreation | 2017 |
| Axiom Live Ltd | Administrative & support | 2018 |
| Axiom Robotech Ltd | Information & communication | 2025 |
| Axorium Environmental Ltd | Water & waste | 2026 |
| AXT Industrial Services Ltd | Construction | 2026 |
| Axxam Ltd | Real estate | 2024 |
| Axxess Healthcare Ltd | Administrative & support | 2017 |
| AY Access Ltd | Construction | 2019 |
| AY Desserts Limited | Hospitality | 2019 |
| AY Global Ltd | Information & communication | 2012 |
| AY Grill House Limited | Hospitality | 2019 |
| AYA RR Ltd Ltd | Hospitality | 2026 |
| Ayah Tech Limited | Transport & logistics | 2025 |
| Ayamedical & Consultancy Limited | Health & social care | 2023 |
| Ayandeh Sazan Ltd | Real estate | 2023 |
| Ayash FNB Ltd | Extraterritorial | 2021 |
| Aycliffe Hand Car Wash Ltd | Administrative & support | 2019 |
| Ayesha Spice SB Ltd | Hospitality | 2024 |
| Aylesbury Retail Ltd | Wholesale & retail | 2023 |
| AYN Trading Ltd | Wholesale & retail | 2023 |
| Ayoub Fleet Ltd | Transport & logistics | 2025 |
| Ayoub Investment Group Ltd | Professional & scientific | 2023 |
| Ayresome Bites Limited | Hospitality | 2025 |
| Ayresome Car Wash Limited | Administrative & support | 2024 |
| Ayresome Community Enterprise Ltd. | Information & communication | 1995 |
| Ayresome Ltd | Hospitality | 2025 |
| Ayresome Maintenance Ltd | Manufacturing | 2019 |
| Ayrton Renewable Engineers Limited | Administrative & support | 2014 |
| Ayton Consulting Limited | Professional & scientific | 2002 |
| Ayton Energy Limited | Professional & scientific | 2008 |
| Ayton GAS Management Limited | Professional & scientific | 2012 |
| Ayton Investments (Holding Co) Limited | Financial services | 2026 |
| Ayton Investments Limited | Professional & scientific | 2021 |
| Ayton Plumbing, Heating and Bathroom Specialists Ltd | Construction | 2011 |
| AZ Autos and Tyres Ltd | Wholesale & retail | 2022 |
| AZ Commissioning Services Ltd | Construction | 2024 |
| AZ Communications Ltd | Information & communication | 2022 |
| AZ Heat Limited | Energy | 2023 |
| Azad Barbers (NE) Limited | Other services | 2021 |
| Azad Cutz Ltd | Other services | 2021 |
| Azafricanstore Limited | Wholesale & retail | 2025 |
| Azam Property Lettings Ltd | Real estate | 2016 |
| Azeem Tariq Contracting Ltd | Financial services | 2019 |