| ALC Transport Ltd | Transport & logistics | 2023 |
| Alchemax Analytics Limited | Other services | 2017 |
| Alchemy Acquisitions Ltd | Information & communication | 2025 |
| Alcobia's Healthcare Limited | Health & social care | 2023 |
| Aldan Transport Limited | Transport & logistics | 2003 |
| Alderaan Systems Limited | Information & communication | 2017 |
| Alderstone Capital Ltd | Construction | 2025 |
| Alecris Trans Ltd | Transport & logistics | 2024 |
| Aleksmar Ltd | Health & social care | 2021 |
| Alex and Healthcare Ltd | Health & social care | 2021 |
| Alex Driver 09 Ltd | Transport & logistics | 2019 |
| Alex Z Transport Ltd | Transport & logistics | 2025 |
| Alex-Radulescu Ltd | Transport & logistics | 2019 |
| ALEX01 Ltd | Other services | 2025 |
| Alexa EVE Limited | Wholesale & retail | 2022 |
| Alexander Henry Consulting Limited | Professional & scientific | 2012 |
| Alexander Perkins Limited | Construction | 2014 |
| Alexander Swan Insurance Services Limited | Financial services | 2007 |
| Alexander Thomas Developments Ltd | Construction | 2006 |
| Alexandra Fish Bar Ltd | Hospitality | 2021 |
| Alexandra Lagaisse Ltd | Health & social care | 2024 |
| Alexatransport Limited | Transport & logistics | 2015 |
| ALF Premium Ltd | Transport & logistics | 2025 |
| Alfa IT Limited | Information & communication | 2003 |
| Alfil Ltd | Transport & logistics | 2023 |
| Algovia Ltd | Wholesale & retail | 2022 |
| ALI Baba Wholesale Ltd | Wholesale & retail | 2026 |
| Ali's Kebab Bristol Ltd | Hospitality | 2026 |
| Alia Services Ltd | Construction | 2026 |
| Alian’S Car Mechanic Ltd | Wholesale & retail | 2024 |
| Alice Logistics Ltd | Transport & logistics | 2022 |
| Aliem Limited | Professional & scientific | 2024 |
| Alight Arise Ltd | Health & social care | 2022 |
| Alignerstx Limited | Manufacturing | 2024 |
| Alignis Limited | Professional & scientific | 2024 |
| Aligra Personnel (Abingdon) Limited | Administrative & support | 2020 |
| Aligra Personnel (Andover) Limited | Administrative & support | 2020 |
| Aligra Personnel (Hinckley) Limited | Administrative & support | 2020 |
| Aligra Personnel Limited | Administrative & support | 2006 |
| Alina Bumbac Healthcare Ltd | Health & social care | 2022 |
| Alina's Fish & Wingies Limited | Hospitality | 2023 |
| Alina’S Hair & Beauty Ltd | Other services | 2026 |
| Alincris Logistic Ltd | Transport & logistics | 2020 |
| Alison Haigh Limited | Other services | 2019 |
| Alix Freeman Limited | Professional & scientific | 2023 |
| Aljoeebay Ltd | Wholesale & retail | 2022 |
| ALK Entertainment LLP | | 2024 |
| Alkaline Property Limited | Construction | 2018 |
| Alkison Ltd | Wholesale & retail | 2016 |
| ALL Ears Avow Ltd | Wholesale & retail | 2023 |
| ALL Here Ltd | Wholesale & retail | 2024 |
| ALL in ALL Solutions Limited | Information & communication | 2007 |
| ALL in One Installations Ltd | Construction | 2022 |
| ALL Minds Holding Ltd | Financial services | 2021 |
| ALL Saints Travel Ltd | Administrative & support | 2003 |
| ALL Seasons Tree Solutions Ltd | Professional & scientific | 2015 |
| ALL SET Security Ltd | Administrative & support | 2017 |
| ALL Star Hockey Ltd | Wholesale & retail | 2009 |
| ALL Under 1 Roof Home Improvements Ltd | Other services | 2025 |
| ALL YOU CAN Heat GAS Services Ltd | Construction | 2019 |
| ALL Your Prey Ltd | Professional & scientific | 2021 |
| All-Ko Smart Properties Ltd | Real estate | 2024 |
| All-Koms Ltd | Information & communication | 2020 |
| Allan Caple Design Contracting Ltd | Professional & scientific | 2024 |
| Alldigital Marketing Ltd | Information & communication | 2015 |
| Alldigital Systems Ltd | Professional & scientific | 2025 |
| Allegiant Developments Ltd | Construction | 2021 |
| Allen Atlas Co Ltd | Administrative & support | 2026 |
| Allen Consulting Group Ltd | Professional & scientific | 2016 |
| Allen Landscapes Swindon Ltd | Administrative & support | 2025 |
| Allen Salter Wealth Management Ltd | Financial services | 2000 |
| Allen Talent Group Ltd | Real estate | 2026 |
| Allen’S Recovery Ltd | Wholesale & retail | 2024 |
| Allergy Free Goods Ltd | Wholesale & retail | 2024 |
| Allesta Guardians Ltd | Other services | 2025 |
| Allfare Ltd | Other services | 2019 |
| Allford Bryant Business Advisors Ltd | Professional & scientific | 2009 |
| Alliance Healthcare Initiatives Limited | Professional & scientific | 2022 |
| Allied Dunbar Assurance PLC | Financial services | 1965 |
| Allied Dunbar Financial Services Limited | Extraterritorial | 1975 |
| Allied Dunbar Provident PLC | Extraterritorial | 1964 |
| Allied Wessex Westinsure Limited | Financial services | 2002 |
| Allied Zurich Limited | Professional & scientific | 1998 |
| Allif Ltd | Wholesale & retail | 2023 |
| Allison Court (Swindon) Management Limited | Households | 1996 |
| Allison Jones Physiotherapy Limited | Health & social care | 2011 |
| Allisonmay Care Services Ltd | Health & social care | 2025 |
| Allnutts Wild Supplies Ltd | Wholesale & retail | 2018 |
| Allphaseuk Ltd | Construction | 2019 |
| Allset Luggage Ltd | Manufacturing | 2025 |
| Allsorts GNS Ltd | Wholesale & retail | 2022 |
| Allstar Business Solutions Limited | Administrative & support | 1991 |
| Ally HR Ltd | Professional & scientific | 2019 |
| Allys Care Limited | Health & social care | 2026 |
| Alma Latina Store Limited | Wholesale & retail | 2026 |
| Almeida Parcels Ltd | Transport & logistics | 2024 |
| Almighty Cleaning Limited | Other services | 2009 |
| Alneris Consultancy Ltd | Professional & scientific | 2024 |
| Aloealoe Medical and Scientific Writing Ltd | Professional & scientific | 2025 |
| Alona Clark Installations Limited | Construction | 2017 |