| Audio Visual Arts Limited | Arts & recreation | 1987 |
| Audiotronic Ltd | Construction | 2026 |
| Audit Xprt Limited | Information & communication | 2015 |
| Auditable Engineering Ltd | Information & communication | 2026 |
| Audvis Technology Ltd | Wholesale & retail | 2012 |
| Augmented Intelligence Ltd | Information & communication | 2012 |
| August Energy Limited | Professional & scientific | 2005 |
| Augusta Boat Services Limited | Manufacturing | 2026 |
| Auk-Services Ltd | Construction | 2025 |
| AUM Maintenance Ltd | Construction | 2022 |
| Aumas Limited | Construction | 2006 |
| Aumé Limited | Hospitality | 2025 |
| Auntie Q Limited | Extraterritorial | 2023 |
| Auntie's House CIC | Professional & scientific | 2026 |
| Aunty Vics Limited | Hospitality | 2023 |
| Aura Aesthetics and Beauty Limited | Other services | 2024 |
| Aura Consulting Business Services Limited | Professional & scientific | 2020 |
| Aura PR 2019 Limited | Administrative & support | 2019 |
| Aura Vitana Ltd | Manufacturing | 2023 |
| Auralius Photography Limited | Administrative & support | 2005 |
| Auramed Ltd | Health & social care | 2026 |
| Auraura Limited | Professional & scientific | 2011 |
| Aurea Mediocritas Ltd | Education | 2024 |
| Aureity Limited | Professional & scientific | 2017 |
| Aurelian Astra Holdings Ltd | Real estate | 2026 |
| Aurevon Group Ltd | Wholesale & retail | 2026 |
| Aurevél Ltd | Wholesale & retail | 2026 |
| Auriclear Ltd | Health & social care | 2026 |
| Auriko Limited | Professional & scientific | 2023 |
| Auris Reference Limited | Information & communication | 2011 |
| Aurium Labs Ltd | Information & communication | 2025 |
| Auroh Ltd | Wholesale & retail | 2022 |
| Aurora Energy Advisory Limited | Construction | 2022 |
| Aurora Global Logistics Limited | Transport & logistics | 2026 |
| Aurora Revibe Ltd | Wholesale & retail | 2026 |
| Aurum Estates Group Ltd. | Real estate | 2018 |
| Aurum Exclusive Ltd | Wholesale & retail | 2021 |
| Aurum Private Transport Ltd | Transport & logistics | 2025 |
| Aurum Proxies Ltd | Information & communication | 2024 |
| Aurum Residentials Ltd | Real estate | 2018 |
| Austere Group Limited | Extraterritorial | 2016 |
| Austin Auto Body Work Limited | Manufacturing | 2019 |
| Austin Heath GP Limited | Financial services | 2026 |
| Austin Heath Management Ltd | Households | 2018 |
| Austin Moore & Partners LLP | | 2013 |
| Austin Moore Limited | Other services | 2017 |
| Austin Trauma Services Ltd | Health & social care | 2023 |
| Austinco Limited | Wholesale & retail | 2020 |
| Austin’S Properties Developer Ltd | Construction | 2025 |
| Authentic Africa Market Ltd | Wholesale & retail | 2024 |
| Authenticate Information Systems Limited | Administrative & support | 2013 |
| Autify Digital Ltd | Information & communication | 2020 |
| Auto Body Fixers Ltd | Information & communication | 2023 |
| Auto Car SOR Ltd | Wholesale & retail | 2016 |
| Auto Clean Services Ltd | Administrative & support | 2025 |
| Auto Conway Ltd | Wholesale & retail | 2024 |
| Auto Croft Limited | Wholesale & retail | 2024 |
| Auto Depot Limited | Wholesale & retail | 2010 |
| Auto Diagnostics and Locksmith Ltd | Other services | 2024 |
| Auto Guardians Ltd | Professional & scientific | 2024 |
| Auto Jarecki Ltd | Wholesale & retail | 2015 |
| Auto Ledger House Limited | Wholesale & retail | 2023 |
| Auto Lodge Limited | Transport & logistics | 2012 |
| Auto Luck Ltd | Wholesale & retail | 2019 |
| Auto Professional Ltd | Wholesale & retail | 2018 |
| Auto Reliance Limited | Wholesale & retail | 2025 |
| Auto Reserve Ltd | Wholesale & retail | 2011 |
| Auto Services and MOT Limited | Wholesale & retail | 2017 |
| Auto Services and Repair Limited | Wholesale & retail | 2026 |
| Auto Solutions 2000 Limited | Water & waste | 2009 |
| Auto Storage Land Ltd | Wholesale & retail | 2014 |
| Auto-Klean Filtration Limited | Manufacturing | 2017 |
| Auto-Med Technologies Limited | Manufacturing | 2002 |
| Auto-Tec (Nottm) Limited | Wholesale & retail | 2008 |
| Autobarn Sports Cars Limited | Wholesale & retail | 2014 |
| Autobond Coatings (U.K.) Limited | | 1978 |
| Autocabs Ltd | Transport & logistics | 2025 |
| Autocare & Cycles Limited | Wholesale & retail | 2018 |
| Autocentre Derby Limited | Wholesale & retail | 2020 |
| Autochecked Vehicles Ltd | Wholesale & retail | 2018 |
| Autodraw Limited | Arts & recreation | 2008 |
| Autoelectronic Ltd | Wholesale & retail | 2020 |
| Autofit Windscreens Limited | Wholesale & retail | 2003 |
| Autofix Motor Services Ltd | Wholesale & retail | 2019 |
| Autoforge Limited | Construction | 1988 |
| Autogen Direct Ltd | Wholesale & retail | 2026 |
| Autohouse Motors Ltd | Wholesale & retail | 2024 |
| Autologic Vehicle Services Ltd | Wholesale & retail | 2025 |
| Automated Distribution and Manufacturing Centre CIC | Professional & scientific | 2026 |
| Automated Training Group Ltd | Financial services | 2026 |
| Automateops IT Consultancy Ltd | Information & communication | 2019 |
| Automobile Guide Limited | Wholesale & retail | 2024 |
| Automobile Repairs Ltd | Wholesale & retail | 2026 |
| Automotia Limited | Wholesale & retail | 2020 |
| Automotive Parts Provider Ltd. | Wholesale & retail | 2005 |
| Automotive Spraytech Ltd | Wholesale & retail | 2016 |
| Automotive Training Support Services Limited | Information & communication | 2014 |
| Autopharm Ltd | Wholesale & retail | 2025 |
| Autoplus Nottingham Ltd | Wholesale & retail | 2025 |
| Autopoint UK (Notts) Ltd | Wholesale & retail | 2006 |