| Alpha Corporation Limited | Professional & scientific | 1983 |
| Alpha Development Solutions Ltd | Mining & quarrying | 2026 |
| Alpha Electrix Ltd | Construction | 2019 |
| Alpha Flame Chauffeurs Ltd | Transport & logistics | 2024 |
| Alpha General Developments Ltd | Construction | 2019 |
| Alpha Hire and Logistics Ltd | Transport & logistics | 2026 |
| Alpha Home Improvements London Ltd | Administrative & support | 2008 |
| Alpha Imaging Ltd | Health & social care | 2023 |
| Alpha Investments and Financial Planning Ltd | Financial services | 2010 |
| Alpha Ivor Ltd | Real estate | 2025 |
| Alpha London Ltd | Information & communication | 2019 |
| Alpha Motors Ltd | Wholesale & retail | 2018 |
| Alpha Property Asset Management Limited | Administrative & support | 2000 |
| Alpha Tax Business Services Ltd | Professional & scientific | 2018 |
| Alpha Tax Office Ltd | Extraterritorial | 2025 |
| Alpha UK Limited | Administrative & support | 2009 |
| Alpha Ventilation UK Limited | Administrative & support | 2015 |
| ALPHA13 Ltd | Construction | 2017 |
| ALPHA4U Ltd | Extraterritorial | 2020 |
| Alphaa Constructions Limited | Construction | 2018 |
| Alphabet Pharmacy Limited | Wholesale & retail | 2020 |
| Alphabet Services Limited | Administrative & support | 2015 |
| Alphabeta Company Limited | Wholesale & retail | 2009 |
| Alphabeta Genesis Limited | Financial services | 2020 |
| Alphabeta Properties Ltd | Real estate | 2021 |
| Alphacore Consulting Limited | Information & communication | 2010 |
| Alphagrid Investments (UK) Ltd | Real estate | 2026 |
| Alphagrid Technology Services Ltd. | Information & communication | 2018 |
| Alphen Cleaning Ltd | Administrative & support | 2015 |
| Alphonsus & Co Limited | Professional & scientific | 1996 |
| Alphonsus Enterprises Ltd | Wholesale & retail | 2021 |
| Alphonsus Healthcare Ltd | Health & social care | 2017 |
| Alphonsus Investments Ltd | Real estate | 2017 |
| Alpine Industries UK Ltd | Wholesale & retail | 2024 |
| ALQ Invest Ltd | Real estate | 2025 |
| ALQ Investments Ltd | Real estate | 2021 |
| Alqudus Halal Meat Limited | Wholesale & retail | 2025 |
| Alquran Academy Ltd | Administrative & support | 2024 |
| ALR Partners Limited | Real estate | 2025 |
| Alridha Properties Limited | Real estate | 2021 |
| Alright 2 Limited | Construction | 2014 |
| Alright 3 Limited | Administrative & support | 2014 |
| Alrouya News Ltd | Real estate | 2018 |
| Alshaer Trading Ltd | Construction | 2018 |
| Alshather Consultants Ltd | Health & social care | 2016 |
| Alt-Life Music Ltd | Information & communication | 2018 |
| Alta Casa Care Ltd | Health & social care | 2024 |
| Alta Semita Ltd | Professional & scientific | 2019 |
| Altaf Hemani Ltd | Other services | 2017 |
| Altas Properties Limited | Real estate | 2023 |
| Altasion Limited | Wholesale & retail | 2025 |
| Alter & Native (DM) Limited | Construction | 2025 |
| Alteris Limited | Wholesale & retail | 2022 |
| Alternate Current Publicity Limited | Professional & scientific | 2020 |
| Alternativa One Ltd | Extraterritorial | 2023 |
| Alternative Capital Sources Limited | Administrative & support | 2003 |
| Alternative Infrastructure Investments Limited | Professional & scientific | 2009 |
| Alternative Residential Capital Group Ltd. | Construction | 2021 |
| Alternative Resourcing Limited | Information & communication | 2013 |
| Alternative Supermarket Venture Ltd | Wholesale & retail | 2024 |
| Altiplateau Limited | Information & communication | 2017 |
| Altissima Holdings Limited | Real estate | 2017 |
| Altitude Lighting Limited | Arts & recreation | 2026 |
| ALTITUDE64 Ltd | Information & communication | 2024 |
| Altivery Ltd | Extraterritorial | 2012 |
| Altman Blane & Company Limited | Professional & scientific | 2015 |
| Altomart Limited | Construction | 1991 |
| Altomo Ltd | Financial services | 2017 |
| Alton Care Group Limited | Financial services | 2009 |
| Alton Freehold Ltd | Real estate | 2020 |
| Alton Manor Limited | Health & social care | 2008 |
| Altosec Limited | Information & communication | 2011 |
| Altrad International Ltd | Wholesale & retail | 2008 |
| Altus Event Services Limited | Administrative & support | 2024 |
| Alumni Ventures UK, LLP | | 2025 |
| Alusi ENT Ltd. | Health & social care | 2013 |
| Alvica Medical Ltd | Wholesale & retail | 2023 |
| Alvina (Textiles) Corporation Ltd | Wholesale & retail | 2017 |
| Alvington Prop Co Limited | Real estate | 2014 |
| Alviva Ltd | Administrative & support | 2012 |
| Alwahab Foundation | Health & social care | 2021 |
| Alwahab Limited | Wholesale & retail | 2018 |
| Alwaleed Trading Ltd | Wholesale & retail | 2023 |
| Always Thankful Ltd | Wholesale & retail | 2024 |
| Alxwd Copywriting Limited | Professional & scientific | 2025 |
| Alyassiricar Limited | Financial services | 2025 |
| Alydpharma Ltd | Wholesale & retail | 2023 |
| Alyssas Vision Care Limited | Wholesale & retail | 2021 |
| Alzain Property Management Ltd | Real estate | 2020 |
| AM & Advisors Ltd | Professional & scientific | 2024 |
| AM 1674 Ltd | Transport & logistics | 2026 |
| AM Assets & Acquisitions UK Limited | Real estate | 2016 |
| AM Atmirald Midas Ltd | Other services | 2022 |
| AM Brands Creative Limited | Professional & scientific | 2022 |
| AM Car Wash Ltd | Administrative & support | 2020 |
| AM Corporate Group Ltd | Professional & scientific | 2025 |
| AM Renovair Ltd | Other services | 2025 |
| AM Street Cars Ltd | Wholesale & retail | 2023 |
| AM Web Outlet Limited | Wholesale & retail | 2024 |
| AM Worldwide UK Ltd | Transport & logistics | 2018 |