| Atomic Galaxies Limited | Arts & recreation | 2026 |
| Atomik Growth Ltd | Information & communication | 2023 |
| Atozplanet Ltd | Wholesale & retail | 2021 |
| ATP Consumables Ltd | Wholesale & retail | 2022 |
| ATP Real Estate Partners Ltd | Real estate | 2026 |
| Atqs Construction Limited | Administrative & support | 2026 |
| Atrix Consulting Limited | Professional & scientific | 2023 |
| Atssr Limited | Real estate | 2022 |
| Atta AI Data Limited | Information & communication | 2025 |
| Atta Couriers Ltd | Transport & logistics | 2026 |
| Attache Voyage Limited | Professional & scientific | 2008 |
| Atten Electrical Services Ltd | Construction | 2024 |
| Attilaro Limited | Professional & scientific | 2023 |
| Attitude Swim Coaching Ltd | Education | 2021 |
| Attwater & Sons Limited | Manufacturing | 1939 |
| Attwater Group Limited | Financial services | 2025 |
| AU Accountants Limited | Professional & scientific | 2019 |
| AU CP Limited | Financial services | 2018 |
| Auction Court (Longridge) Management Company Limited | Households | 2016 |
| Auction Eats Ltd | Hospitality | 2017 |
| Auction-Pack Limited | Professional & scientific | 2016 |
| Audiebant USA Ltd | Information & communication | 1999 |
| Audio Products Limited | Wholesale & retail | 1994 |
| Audiokast Ltd | Information & communication | 2012 |
| Audioviz Ltd | Administrative & support | 2023 |
| Audit Direct Ltd | Extraterritorial | 2013 |
| Audit Trail Technologies Limited | Information & communication | 2014 |
| Audry PR1 Ltd | Arts & recreation | 2023 |
| Augeas LLP | | 2024 |
| Aughton F Limited | Manufacturing | 2020 |
| Augmented Business Intelligence Limited | Information & communication | 2020 |
| Augmun Solutions Ltd | Professional & scientific | 2022 |
| August Sutton Limited | Other services | 2024 |
| AUK Enterprises Limited | Information & communication | 2017 |
| Auldene Garden Tools Limited | Wholesale & retail | 2002 |
| AUM Estates Ltd | Real estate | 2025 |
| AUM Rentals Limited | Real estate | 2023 |
| Auntee Technologies Ltd | Information & communication | 2026 |
| Auntie's Doggie Daycare Limited | Other services | 2014 |
| Aunties Doggie (Franchise) Limited | Professional & scientific | 2015 |
| Aunty Dolly's Preston Ltd | Wholesale & retail | 2012 |
| Aura Drop Ltd | Wholesale & retail | 2022 |
| Aura Longridge Ltd | Real estate | 2024 |
| Aureate Events Limited | Hospitality | 2025 |
| Aurelian Delivery Ltd | Transport & logistics | 2023 |
| Aurelias Property Group Ltd | Real estate | 2026 |
| Aurm Skin Clinic Ltd | Real estate | 2025 |
| Auro Occupational Health Ltd | Health & social care | 2025 |
| Aurora and Tilly Ltd | Wholesale & retail | 2023 |
| Aurora Resources Limited | Extraterritorial | 2007 |
| Aurum Homes Limited | Construction | 2014 |
| Aurzn Developments Limited | Construction | 2024 |
| AUS Builders Ltd | Construction | 2019 |
| Austien Construction Ltd | Construction | 2025 |
| Austin GEO Solutions Ltd. | Professional & scientific | 2006 |
| Austin Thomas Plant and Machinery Ltd | Wholesale & retail | 2025 |
| Austin Walmsley Ltd | Manufacturing | 2002 |
| Austin Watson Limited | Construction | 2002 |
| Austin White & Company Limited | Wholesale & retail | 1964 |
| Austin-Lenika Project Services Limited | Professional & scientific | 2002 |
| Autech Limited | Administrative & support | 2004 |
| Authentic Cuisine Preston Ltd | Hospitality | 2018 |
| Authentic Place Limited | Professional & scientific | 2012 |
| Authenticstock Limited | Wholesale & retail | 2008 |
| Auto Bazaar Ltd | Wholesale & retail | 2018 |
| Auto Body Centre Preston Ltd | Wholesale & retail | 2019 |
| Auto Clean Preston Ltd | Administrative & support | 2026 |
| Auto Hub Group Tarleton Ltd | Wholesale & retail | 2025 |
| Auto Link Transport Ltd | Transport & logistics | 2025 |
| Auto Salvage International Limited | Wholesale & retail | 2012 |
| Auto-Motivate Training and Consulting Limited | Professional & scientific | 2018 |
| Autoforensic Limited | Professional & scientific | 2013 |
| Autogearbox Repair Services Limited | Wholesale & retail | 2003 |
| Automated Fuelling Systems (Northern) Limited | | 1986 |
| Automatic Transmissions (Preston) Ltd | Wholesale & retail | 2012 |
| Automation Protocols Services Ltd | Information & communication | 2025 |
| Automatrix PVT Ltd | Wholesale & retail | 2025 |
| Automet Limited | Manufacturing | 2002 |
| Automet Properties Limited | Real estate | 2003 |
| Automotive 1 Ltd | Manufacturing | 2024 |
| Automotive Direct Hire Limited | Administrative & support | 2025 |
| Automotive Export Holdings Limited | Financial services | 2025 |
| Automotive Export Limited | Wholesale & retail | 2000 |
| Automotive Insights & Research Services Ltd | Professional & scientific | 2025 |
| Autonation UK ( Car Sales ) Limited | Wholesale & retail | 2025 |
| Autopoint Forecourt Limited | Real estate | 2015 |
| Autopoint Properties Ltd | Real estate | 2016 |
| Autorov Limited | Professional & scientific | 2012 |
| Autoscan Diagnostics Ltd | Wholesale & retail | 2016 |
| Autoscratchrepairs Ltd | Wholesale & retail | 2019 |
| Autovolt Ltd | Information & communication | 2025 |
| Autumn Leaves Solutions Ltd | Real estate | 2024 |
| AUTUMN8 Ltd | Professional & scientific | 2018 |
| Auxinova Technologies Ltd | Wholesale & retail | 2024 |
| AV Online (NW) Ltd | Wholesale & retail | 2022 |
| AV2EVENTS Limited | Professional & scientific | 2013 |
| AV8 Consultancy Ltd | Health & social care | 2021 |
| AVA Builders Limited | Construction | 2015 |
| AVA Motors (Leyland) Ltd | Wholesale & retail | 2025 |
| Avacab Ltd | Transport & logistics | 1999 |