| Aurum Archaeology Limited | Administrative & support | 2025 |
| Aurum Shipbroking Ltd | Professional & scientific | 2022 |
| Austalex Limited | Wholesale & retail | 2013 |
| Austen Allen Sales & Marketing Limited | Wholesale & retail | 2003 |
| Austen Leisure Ltd | Arts & recreation | 2016 |
| Austen XXL Ltd | Arts & recreation | 2026 |
| Austhorpe Carpets Limited | Wholesale & retail | 2012 |
| Austin Dransfield Morpeth Limited | Real estate | 1981 |
| Authenthai Day Ltd | Hospitality | 2022 |
| Authenthai Restaurant Limited | Hospitality | 2026 |
| Authenthai Takeaway Limited | Hospitality | 2022 |
| Authentic Chinese Ltd | Hospitality | 2021 |
| Authentic Gear Ltd | Wholesale & retail | 2014 |
| Authentic Pizzeria Ltd | Hospitality | 2025 |
| Authentic Teaching CIC | Public administration | 2025 |
| Authenticate Certify Grade Limited | Other services | 2025 |
| Autism Union Ltd | Administrative & support | 2018 |
| Auto Attercliffe Limited | Wholesale & retail | 2025 |
| Auto Detail (South Yorkshire) Limited | Wholesale & retail | 2025 |
| Auto Euro Empire Ltd | Wholesale & retail | 2020 |
| Auto Motor Group Limited | Wholesale & retail | 2026 |
| Auto Part & Body Solution Ltd | Wholesale & retail | 2025 |
| Auto Prestiege Ltd | Wholesale & retail | 2019 |
| Auto-Mectec Ltd | Wholesale & retail | 2025 |
| Auto-Trek Limited | Wholesale & retail | 2015 |
| Autobritain Ltd | Professional & scientific | 2013 |
| Autobuzz Limited | Wholesale & retail | 2024 |
| Autocars of Tupton Limited | Real estate | 1971 |
| Autoclique Ltd | Wholesale & retail | 2024 |
| Autocraft Services (EST. 1977) Limited | Wholesale & retail | 2012 |
| Autodrift Motors Ltd | Wholesale & retail | 2024 |
| Autofix Plus Ltd | Wholesale & retail | 2024 |
| Autofold Systems Limited | Extraterritorial | 2004 |
| Autogate Supplies Limited | Wholesale & retail | 2018 |
| Autograph Aesthetics Ltd | Other services | 2020 |
| Autohaus Dolby Ltd | Wholesale & retail | 2012 |
| Autohunteruk Limited | Wholesale & retail | 2023 |
| Autoillume Ltd | Wholesale & retail | 2018 |
| Autolam UK Ltd | Manufacturing | 2020 |
| Autoline Traders UK Ltd | Wholesale & retail | 2025 |
| Automate AI Group Ltd | Information & communication | 2024 |
| Automatic Knowledge Ltd | Information & communication | 2019 |
| Automatic Vending Machines Limited | Hospitality | 2011 |
| Automating Health Ltd | Information & communication | 2024 |
| Automation Hive Ltd | Information & communication | 2025 |
| Automax Motor Engineers Ltd | Manufacturing | 2020 |
| Automins Ltd | Information & communication | 2023 |
| Automotivate Fleet Solutions Ltd | Wholesale & retail | 2025 |
| Automotivate Holdings Ltd | Financial services | 2025 |
| Automotivate Leasing Ltd | Financial services | 2025 |
| Automotive Business Intelligence Ltd | Information & communication | 2019 |
| Autonet Law LLP | | 2012 |
| Autonomous Software Ltd | Extraterritorial | 2026 |
| Autonur Ltd | Wholesale & retail | 2025 |
| Autoplus Windscreens Ltd | Wholesale & retail | 2011 |
| Autosolutions Runcorn Ltd | Wholesale & retail | 2019 |
| Autospec Blackpool Ltd | Wholesale & retail | 2010 |
| Autotecnic Group Ltd | Wholesale & retail | 2024 |
| Autotecnic Limited | Wholesale & retail | 2005 |
| Autotronix Developments Limited | Wholesale & retail | 2012 |
| Autotronix Vehicle Diagnostics Limited | Wholesale & retail | 2007 |
| Autoviz Motors Ltd | Wholesale & retail | 2024 |
| Autralas Limited | Other services | 2013 |
| Auttreats Ltd | Extraterritorial | 2012 |
| AUX BON Vivant Ltd | Wholesale & retail | 2025 |
| Auxilion UK Limited | Information & communication | 2015 |
| Auxilium Fintech Limited | Information & communication | 2026 |
| AV Couriers Ltd | Transport & logistics | 2020 |
| AV Machine Tool Support Limited | Manufacturing | 2013 |
| AV Sharples Limited | Hospitality | 2026 |
| AV Shop Ltd | Information & communication | 2016 |
| AVA Minimarket Limited | Wholesale & retail | 2023 |
| AVA Productions Limited | Information & communication | 2004 |
| AVA Property Developers Ltd | Real estate | 2026 |
| AVA Softech Ltd | Construction | 2013 |
| AVA Turf Supplies Limited | Administrative & support | 2012 |
| AVA Yazid Productions Limited | Information & communication | 2017 |
| Avail Systems Limited | Construction | 2010 |
| Available Bands Ltd | Arts & recreation | 2025 |
| Avajó Limited | Other services | 2024 |
| Avalem Limited | Administrative & support | 2015 |
| Avalon Bespoke Services Limited | Manufacturing | 2015 |
| Avalon Collectable Gifts Limited | Wholesale & retail | 2024 |
| Avant Garde Drinks Ltd | Wholesale & retail | 2011 |
| Avant Garde Leisure Ltd | Hospitality | 2013 |
| Avanti Logistics + Shipping Limited | Transport & logistics | 2010 |
| Avara Media Ltd | Information & communication | 2026 |
| Avavivys Ltd | Other services | 2024 |
| AVB Management Limited | Professional & scientific | 2025 |
| Aveed Limited | Real estate | 2025 |
| Avekshaa Technologies Limited | Information & communication | 2025 |
| Aveley Engineering Limited | Manufacturing | 2002 |
| Aveley Limited | Real estate | 2006 |
| Avella Living Ltd | Hospitality | 2025 |
| Avensys Networks Limited | Information & communication | 2012 |
| Aventa Motors Ltd | Wholesale & retail | 2022 |
| Avenu Recs Ltd | Information & communication | 2025 |
| Avenue Investment Management Ltd | Real estate | 2020 |
| Avermann UK Limited | Manufacturing | 2026 |
| Averybay Limited | Agriculture & fishing | 1995 |