| Atob Car Sale Limited | Wholesale & retail | 2026 |
| Atom Facilities Management Ltd | Other services | 2024 |
| Atom Fit OUT Construction & Design Ltd | Other services | 2024 |
| Atom Food & Drink Ltd | Other services | 2024 |
| Atom Talent Management Limited | Professional & scientific | 2022 |
| Atomic Events Ltd | Hospitality | 2026 |
| Atoms Medical Ltd | Health & social care | 2024 |
| Aton.Amz Ltd | Wholesale & retail | 2019 |
| Atoz Cars Limited | Wholesale & retail | 2019 |
| Atoz Pick Ltd | Wholesale & retail | 2025 |
| ATP Medical Limited | Wholesale & retail | 2016 |
| ATP Services Limited | Transport & logistics | 2022 |
| Atriolend Limited | Professional & scientific | 2025 |
| ATS Haulage Ltd | Transport & logistics | 2024 |
| Attack the Snack Ltd | Hospitality | 2026 |
| Attain Legal Costs Management Limited | Administrative & support | 2002 |
| Attenborough Learning Trust | Education | 2018 |
| Attenborough Trimmings Limited | Wholesale & retail | 2005 |
| Attfield's Farm Shop Limited | Wholesale & retail | 2004 |
| Attic Holdings Limited | Financial services | 2021 |
| Attila & Homer Limited | Real estate | 2026 |
| Attila Construction Limited | Construction | 2024 |
| Attila Developments Limited | Real estate | 2024 |
| Attila Electrical Limited | Construction | 2024 |
| Attila Property Holdings Ltd | Real estate | 2023 |
| Attwall Limited | Real estate | 2012 |
| Atwal Developments Limited | Real estate | 2020 |
| Atwill Properties Limited | Real estate | 2024 |
| AU Bakery Limited | Wholesale & retail | 2025 |
| AU Sales Ltd | Wholesale & retail | 2021 |
| AU Wealth Limited | Professional & scientific | 2025 |
| AUA Autos Limited | Wholesale & retail | 2023 |
| Aucho Leisure Limited | Hospitality | 2024 |
| Aucho Leisure Louth Limited | Hospitality | 2025 |
| Auction Brokers Ltd | Real estate | 2019 |
| Audibly Visual Entertainment Ltd | Construction | 2023 |
| Audio Alpha Ltd | Professional & scientific | 2018 |
| Audio Industries Ltd | Information & communication | 2019 |
| Audio Lounge Leicester Ltd | Wholesale & retail | 2020 |
| Audio Visual Electronics Ltd | Wholesale & retail | 2024 |
| Audioflix Ltd | Information & communication | 2025 |
| Audiyo Hearing Ltd | Wholesale & retail | 2022 |
| Audrey Competitions Limited | Arts & recreation | 2024 |
| Augmented Imagination Limited | Administrative & support | 2017 |
| Augmented Minds Limited | Information & communication | 2017 |
| Augustine Bridge Ventures Ltd | Real estate | 2025 |
| AUI Estates Ltd | Real estate | 2024 |
| Aujla Logistics Ltd | Transport & logistics | 2025 |
| Aulakh Capital Ltd | Real estate | 2025 |
| Auld’S Logistics Ltd | Transport & logistics | 2026 |
| AUM Astar Limited | Real estate | 2015 |
| AUM Construction (UK) Ltd | Construction | 2013 |
| AUM Home Automation Ltd | Construction | 2020 |
| AUM Investments Leicester Limited | Real estate | 2012 |
| AUM Properties Ltd | Construction | 2022 |
| AUM Transport Ltd | Transport & logistics | 2025 |
| AUM Wealth Management Limited | Real estate | 2016 |
| Aumi Limited | Wholesale & retail | 2025 |
| Aunty Shana's Little Kitchen Ltd | Hospitality | 2026 |
| Aunty’S Coffee Shop Ltd | Hospitality | 2026 |
| AUR Trading Hub UK Limited | Wholesale & retail | 2024 |
| Aura Aesthetics by Shriti Ltd | Other services | 2024 |
| Aura Boutique Ltd | Wholesale & retail | 2014 |
| Aura Designs Ltd | Manufacturing | 2014 |
| Aura Homes Letting Limited | Real estate | 2025 |
| Aura Plumbing and GAS Ltd | Construction | 2026 |
| Aura Spatial Designs Limited | Construction | 2002 |
| Auraclean Services Ltd | Administrative & support | 2025 |
| Auram Living Ltd | Real estate | 2025 |
| Aurangzaib Ltd | Wholesale & retail | 2025 |
| Aurapeak Limited | Manufacturing | 2026 |
| Aurden Ltd | Manufacturing | 2017 |
| Aurea Finch Ltd | Wholesale & retail | 2025 |
| Auream Foods Limited | Wholesale & retail | 2023 |
| Aurelia Collection Limited | Wholesale & retail | 2025 |
| Aurelia Constructions Ltd | Construction | 2015 |
| Aurelius Assets Ltd | Real estate | 2025 |
| Aurelius UK Holdings Ltd | Professional & scientific | 2025 |
| Aurelli Estates Ltd | Real estate | 2026 |
| Aurelux Ltd | Wholesale & retail | 2026 |
| Aurex Sciences Ltd | Manufacturing | 2026 |
| Auricle Limited | Extraterritorial | 2022 |
| Auriferous Limited | Professional & scientific | 2014 |
| Auriga Psychiatry Ltd | Health & social care | 2022 |
| Aurin and Juhi Ltd | Real estate | 2020 |
| Auro Collective Ltd | Manufacturing | 2025 |
| Aurora Car Sales Ltd | Wholesale & retail | 2025 |
| Aurora Cosmetics (Wholesale) Limited | Wholesale & retail | 2011 |
| Aurora Investment Properties LLP | | 2026 |
| Aurora Life Child and Adult Services Limited | Health & social care | 2026 |
| Aurora Nottingham Limited | Professional & scientific | 2025 |
| Aurora Outdoor Media Ltd | Professional & scientific | 2024 |
| Aurora Property Group Ltd | Arts & recreation | 2026 |
| Aurora Technologies Limited | Information & communication | 1999 |
| Aurora Wealth Management Limited | Financial services | 2012 |
| Auroraz Ltd | Wholesale & retail | 2018 |
| Aursu Ltd | Financial services | 2024 |
| Aurum Acquisitions Limited | Wholesale & retail | 2004 |
| Aurum Electrical Installations Ltd | Manufacturing | 2015 |
| Aurum Jewels Ltd | Wholesale & retail | 2022 |