| Atlas Teachers Limited | Administrative & support | 2018 |
| ATM X Ltd | Other services | 2024 |
| Atma Enterprises Limited | Real estate | 2026 |
| Atma Health & Fitness Ltd | Arts & recreation | 2026 |
| ATO Trade Ltd | Health & social care | 2020 |
| ATO9 Ltd | Wholesale & retail | 2023 |
| Atomic Elements Consulting Ltd | Information & communication | 2025 |
| Atomic Parenting Ltd | Wholesale & retail | 2025 |
| Atoztax Ltd | Professional & scientific | 2025 |
| ATR Care Limited | Health & social care | 2019 |
| ATR Travel Ltd | Administrative & support | 2022 |
| Atrx Enterprises Ltd | Wholesale & retail | 2023 |
| ATS Racing Limited | Arts & recreation | 2022 |
| Attcn Ltd | Health & social care | 2021 |
| ATU Limited | Arts & recreation | 2016 |
| AU Business Specialist Ltd | Real estate | 2024 |
| Auction 4 U Limited | Professional & scientific | 2005 |
| Auction Local Ltd | Real estate | 2025 |
| Audie Homer Holdings Limited | Financial services | 2024 |
| Audio and Display Solutions Limited | Information & communication | 2009 |
| Audiology Unit Materials Limited | Health & social care | 2001 |
| AUDIOLOGY4U Limited | Health & social care | 2025 |
| Augustinian Properties Ltd | Real estate | 2022 |
| Aujla Business Ltd | Transport & logistics | 2025 |
| Aulton & Butler Limited | Manufacturing | 1955 |
| Aulton Building Contractors Limited | Construction | 2016 |
| AUM Group Limited | Professional & scientific | 2018 |
| AUM Healthcare Limited | Wholesale & retail | 2002 |
| AUM Investco Limited | Financial services | 2026 |
| Aunt Sally's (Walsall) Ltd | Wholesale & retail | 2013 |
| Aura Decor Ltd | Manufacturing | 2022 |
| Aura Dordon Ltd | Hospitality | 2025 |
| Aura Foods Ltd | Hospitality | 2026 |
| Aura Jewellers Ltd | Other services | 2024 |
| Aura Metals Recycling Ltd | Wholesale & retail | 2024 |
| Aurilm Limited | Education | 2026 |
| Aurora Deluxe Properties Ltd | Real estate | 2023 |
| Aurora Electronics (UK) Limited | Wholesale & retail | 1999 |
| Aurora Resourcing Holdings Limited | Administrative & support | 2017 |
| Aurora Resourcing Ltd | Administrative & support | 2013 |
| Aurora Square Ltd | Wholesale & retail | 2025 |
| Auroraplunge Limited | Wholesale & retail | 2026 |
| Austin Drywall Ltd | Construction | 2023 |
| Autara Group Ltd | Financial services | 2025 |
| Authentic Secretarial Services Limited | Professional & scientific | 2015 |
| Authentic Services Limited | Professional & scientific | 2004 |
| Author L Gray Limited | Arts & recreation | 2019 |
| Auto Connect (Walsall) Limited | Wholesale & retail | 2019 |
| Auto FM Limited | Wholesale & retail | 2018 |
| Auto Jerry G Ltd | Wholesale & retail | 2025 |
| Auto Parts Walsall Limited | Wholesale & retail | 2014 |
| Auto Prestige Ltd | Wholesale & retail | 2020 |
| Auto Trade Services Ltd | Wholesale & retail | 2019 |
| Autograph Consortium Limited | Financial services | 2009 |
| Autograph Retail Limited | Wholesale & retail | 2010 |
| Autohub Walsall Limited | Wholesale & retail | 2026 |
| Automad Ltd | Wholesale & retail | 2023 |
| Automaintenance Ltd | Professional & scientific | 2026 |
| Automatic AI Ltd | Administrative & support | 2026 |
| Automatic Door Solutions Ltd | Manufacturing | 2025 |
| Automation Engineering & Controls Limited | Professional & scientific | 2019 |
| Automation Labs Ltd | Information & communication | 2026 |
| Automation Workshop Ltd | Financial services | 2024 |
| Automotive Central Mobile Ltd | Wholesale & retail | 2026 |
| Automotive Solution Services Limited | Wholesale & retail | 2024 |
| Autoplate Midlands Limited | Arts & recreation | 1990 |
| Autoshop Limited | Real estate | 1996 |
| Autotec-Uk Ltd | Wholesale & retail | 2019 |
| Autotrade Lichfield Ltd | Wholesale & retail | 2026 |
| Autumn Breeze Healthcare Ltd | Health & social care | 2025 |
| Autumn Leaves Furniture Outlet Ltd | Wholesale & retail | 2013 |
| Auvation Software Limited | Information & communication | 1987 |
| Auxilium Merchant Ltd | Wholesale & retail | 2017 |
| AV and DV Properties Ltd | Real estate | 2026 |
| AV Construction Pros Ltd | Construction | 2026 |
| AV Digital Solutions Limited | Administrative & support | 2023 |
| AV Installation Team Limited | Professional & scientific | 2020 |
| Av-Me Holdings Limited | Financial services | 2022 |
| AV25 Properties Ltd | Real estate | 2025 |
| AV2RENT Limited | Administrative & support | 2020 |
| Avail Education Limited | Education | 2022 |
| Avamei UK Ltd | Public administration | 2019 |
| Avamy Estates Ltd | Real estate | 2025 |
| Avana Healthcare Limited | Wholesale & retail | 2022 |
| Avana Holdings Limited | Professional & scientific | 2023 |
| Avana Limited | Real estate | 2019 |
| Avani Traffic Solutions Limited | Professional & scientific | 2018 |
| Avantgarde Pharma Ltd | Wholesale & retail | 2011 |
| Avanti 8 Ltd | Professional & scientific | 2019 |
| Avaran Limited | Real estate | 2023 |
| AVC Courier Ltd | Transport & logistics | 2022 |
| Aventiq Consulting Limited | Administrative & support | 2016 |
| Aveo Europe Limited | Wholesale & retail | 2008 |
| Averta Employment Lawyers LLP | | 2010 |
| Avery Hudson Properties Ltd | Real estate | 2020 |
| Avey Investments Limited | Real estate | 2017 |
| AVG Offshore Engineering Ltd | Professional & scientific | 2024 |
| Avicential Limited | Wholesale & retail | 2020 |
| Avidity Training Limited | Education | 2012 |
| Avio Performance Group Ltd | Wholesale & retail | 2023 |