| Astralorb Limited | Wholesale & retail | 2024 |
| AT Control Solutions Ltd | Professional & scientific | 2026 |
| AT Hire Ltd | Administrative & support | 2019 |
| Ataxor Ltd | Other services | 2019 |
| ATB Pipeline Consultancy Limited | Professional & scientific | 2025 |
| ATD Photography Ltd | Extraterritorial | 2010 |
| ATE Land Solutions Limited | Mining & quarrying | 2021 |
| Ategol Ltd | Transport & logistics | 2022 |
| ATG Technical Services Ltd | Professional & scientific | 2026 |
| Athena Home Care Limited | Health & social care | 2023 |
| Athena Wills Ltd | Professional & scientific | 2016 |
| Atitlan Investments (UK) Limited | Real estate | 2017 |
| Atlantic Colonial Properties Limited | Real estate | 2016 |
| Atlantic Infotech Limited | Information & communication | 2007 |
| Atlas Resourcing Ltd | Administrative & support | 2023 |
| ATM Heating Services Ltd | Construction | 2021 |
| Atom LED Lighting Ltd | Wholesale & retail | 2019 |
| Atom Web Ltd | Information & communication | 2013 |
| Attah and Sons Ltd | Wholesale & retail | 2022 |
| Attic Store Limited | Construction | 2024 |
| Atticus Finch Group Limited | Information & communication | 2024 |
| Atuco Limited | Professional & scientific | 2025 |
| ATW Couriers Ltd | Transport & logistics | 2019 |
| ATW Property Services Ltd | Real estate | 2025 |
| Atwal-Gill Properties Ltd | Real estate | 2025 |
| Auditt - Technology Consulting Ltd | Information & communication | 2023 |
| Auntie Hol’S Doggy Daycare Ltd | Hospitality | 2022 |
| Aura Capital Estates Limited | Wholesale & retail | 2016 |
| Aura Health Care Ltd | Administrative & support | 2020 |
| Aurea Vale Viridis Ltd | Financial services | 2025 |
| Auredi Ltd | Other services | 2020 |
| Auric Signature Ltd | Administrative & support | 2025 |
| Aurimxs Ltd | Construction | 2019 |
| Aurora Warehouse Storage Systems Ltd | Construction | 2023 |
| Ausbus Ltd | Wholesale & retail | 2022 |
| Ausley Consultants Limited | Professional & scientific | 2022 |
| Autism Family Dynamics Limited | Health & social care | 2024 |
| Auto Active Car Repairs & Recovery Ltd | Wholesale & retail | 2025 |
| Auto Cosmetic Paint Solutions Ltd | Wholesale & retail | 2021 |
| Auto Growth Limited | Professional & scientific | 2024 |
| Auto KPR Ltd | Wholesale & retail | 2017 |
| Auto Mechanical & Gailey Recovery Limited | Wholesale & retail | 2001 |
| Auto Recode Shropshire Ltd | Wholesale & retail | 2021 |
| Auto-Tech of Telford Ltd | Wholesale & retail | 2017 |
| Autocraft Express Telford Ltd | Wholesale & retail | 2014 |
| Autocraft Holdings Telford Ltd | Financial services | 2019 |
| Autocraft Telford Ltd | Wholesale & retail | 2010 |
| Autoflow Solutions Ltd | Administrative & support | 2025 |
| Autokai Ltd | Wholesale & retail | 2025 |
| Automaker TV & Media Limited | Information & communication | 2011 |
| Automated Grounds Maintenance Ltd | Administrative & support | 2023 |
| Automation by Design Ltd | Information & communication | 2015 |
| Automation X Ltd | Professional & scientific | 2023 |
| Autoshine and Tinting Ltd | Wholesale & retail | 2010 |
| Autoxport Ltd | Wholesale & retail | 2012 |
| Auxilium Property Management Limited | Real estate | 2019 |
| AV Link Ltd | Wholesale & retail | 2024 |
| AV Pipework Services Ltd | Manufacturing | 2025 |
| Avalanche Aviation Limited | Transport & logistics | 2011 |
| Avantis Trade Limited | Construction | 2025 |
| AVF Global Limited | Financial services | 2019 |
| Aviator Transport Ltd | Transport & logistics | 2020 |
| Avion Electrical Ltd | Transport & logistics | 2003 |
| Avioverse Limited | Manufacturing | 2022 |
| Aviramp GSE Limited | Manufacturing | 2015 |
| Aviramp Limited | Manufacturing | 2009 |
| Avococo Ltd | Wholesale & retail | 2021 |
| AVS Transport Ltd | Transport & logistics | 2021 |
| AW Locksmiths Ltd | Administrative & support | 2012 |
| AWB Mobility Limited | Wholesale & retail | 2025 |
| Awenna Ltd | Other services | 2019 |
| Awesome Kitchen Ltd | Hospitality | 2025 |
| AWS Renovations & Lettings Ltd | Real estate | 2025 |
| AWT Catering Ltd | Hospitality | 2018 |
| Axel Haulage Ltd | Transport & logistics | 2024 |
| Axiomiretech Ltd | Information & communication | 2025 |
| Axis Gaming Ltd | Wholesale & retail | 2023 |
| Axolobby Properties Ltd | Real estate | 2026 |
| Axonic Connect Cables Ltd | Wholesale & retail | 2026 |
| Axyz Automation (U.K.) Limited | Manufacturing | 1996 |
| Ayada Ltd | Real estate | 2024 |
| Aydin Construction Services Ltd | Professional & scientific | 2019 |
| Ayeeko Ventures & Properties Ltd | Construction | 2026 |
| Azafik Ltd | Other services | 2019 |
| Azam Consultancy Limited | Professional & scientific | 2019 |
| Azart Solutions Ltd | Professional & scientific | 2025 |
| Azawu Ltd | Other services | 2019 |
| AZR Financial Services Ltd | Extraterritorial | 2021 |
| Aztek IT Solutions Limited | Professional & scientific | 2017 |
| Azzuro Ltd | Other services | 2019 |
| B & B (Norton) Limited | Wholesale & retail | 2004 |
| B & M Bird (Holdings) Limited | Construction | 2007 |
| B & M Bird (Roofing) Limited | Construction | 2003 |
| B & T'S Fish Bar Ltd | Hospitality | 2026 |
| B Brothers Ltd | Transport & logistics | 2011 |
| B Independent Financial Services Limited | Financial services | 2009 |
| B L Surety Limited | Real estate | 2018 |
| B M Perfect Food Ltd | Hospitality | 2017 |
| B T R International Limited | Professional & scientific | 1969 |
| B T R Property Holdings Limited | Administrative & support | 1864 |