| Alpha Security Essex Limited | Administrative & support | 2019 |
| Alpha Squared Partners Ltd | Administrative & support | 2020 |
| Alpha Trading Solutions Ltd | Wholesale & retail | 2025 |
| ALPHA2025 Limited | Construction | 2015 |
| Alphabyte IT Limited | Information & communication | 2009 |
| Alphaemmy Company Limited | Wholesale & retail | 2019 |
| Alphafly Ltd | Professional & scientific | 2025 |
| Alphakey Group Limited | Information & communication | 2020 |
| Alphaluxx Ltd | Wholesale & retail | 2021 |
| Alphapapagolf FM Services Ltd | Professional & scientific | 2019 |
| Alpharate Limited | Hospitality | 2015 |
| Alpharts Limited | Administrative & support | 2020 |
| Alphascript Limited | Professional & scientific | 2000 |
| Alphasea Limited | Real estate | 2015 |
| Alphasonic Limited | Wholesale & retail | 2017 |
| Alphaworks Global Ltd | Construction | 2025 |
| Alpine Serenity Ltd | Education | 2026 |
| Alprof Ltd | Construction | 2013 |
| Alqadsya Car Sales Ltd | Other services | 2023 |
| Alraad Limited | Administrative & support | 2026 |
| Alraid Property Maintenance Ltd | Construction | 2024 |
| Alrasheed Barber Ltd | Other services | 2018 |
| ALS Financial Solutions Limited | Financial services | 2012 |
| Alsalam Roastery Ltd | Hospitality | 2024 |
| Alsaranglobal Limited | Wholesale & retail | 2025 |
| Alsari Ltd | Wholesale & retail | 2025 |
| Alse Transports Ltd | Transport & logistics | 2025 |
| Alshom Ltd | Construction | 2019 |
| Alsia PC | | 2017 |
| Alsinan Ltd | Wholesale & retail | 2025 |
| Alssamad Limited | Hospitality | 2025 |
| Alston House Craf Ltd | Hospitality | 2020 |
| ALT Wellness Group Ltd | Health & social care | 2025 |
| Alta Design & Development Limited | Construction | 2018 |
| Alta Growth Ltd | Administrative & support | 2026 |
| Alta Performa Ltd | Education | 2025 |
| Alta Vista Partners Limited | Professional & scientific | 2025 |
| Altaf Sandfield Limited | Hospitality | 2018 |
| Altaform Limited | Construction | 2018 |
| Altai Mountain Shilajit Ltd | Hospitality | 2021 |
| Altar London Limited | Wholesale & retail | 2019 |
| Altawafoq Trading Ltd | Wholesale & retail | 2025 |
| Altay Trading Ltd | Wholesale & retail | 2025 |
| Altea Clinical Ltd | Health & social care | 2025 |
| Altera Property Solutions Ltd | Hospitality | 2025 |
| Alternate Media Limited | Professional & scientific | 2018 |
| Alternative Costs Ltd | Professional & scientific | 2014 |
| Alternative Grass Limited | Administrative & support | 2021 |
| Alternative Investor Network Ltd | Education | 2015 |
| Alternative Renewable Energy Ltd | Construction | 2024 |
| Altimaro | Professional & scientific | 2023 |
| Altiora Developments Limited | Real estate | 2021 |
| Altiora Edge Limited | Information & communication | 2026 |
| Altitude Collective Ltd | Administrative & support | 2026 |
| Altitude Imaging Ltd | Professional & scientific | 2017 |
| Altivex Cloud Saas Ltd | Information & communication | 2025 |
| Altkey Locksmiths Ltd | Administrative & support | 2017 |
| Altmore Partnership Limited | Professional & scientific | 2010 |
| Altn Bori Ltd | Wholesale & retail | 2025 |
| Alto A3 Ltd | Wholesale & retail | 2020 |
| Altof & Lyall Limited | Wholesale & retail | 2017 |
| Altoor Ltd | Transport & logistics | 2026 |
| Altra Property Investments Ltd | Extraterritorial | 2016 |
| Altreze Ltd | Information & communication | 2020 |
| Altronn Shipping PTE Ltd | Wholesale & retail | 2025 |
| Altum Organisation Limited | Construction | 2021 |
| Altura Chiropractic Clinic Ltd. | Health & social care | 2011 |
| Alufirm Roofing and Guttering Ltd | Construction | 2025 |
| Aluminium Architectural Installations Ltd | Manufacturing | 2014 |
| Aluminium Bidesign Ltd | Manufacturing | 2019 |
| Aluminium Bidesign UK Group Ltd | Manufacturing | 2018 |
| Aluminor Resourcing Services Ltd | Administrative & support | 2021 |
| Alumniyat for Al-Amaal Al-Raid Ltd | Wholesale & retail | 2025 |
| Alun Edwards Ltd | Information & communication | 2017 |
| Alun Jones Family Law Limited | Professional & scientific | 2010 |
| Alun Tomkinson Ltd | Health & social care | 2016 |
| Alur Digital Ltd | Administrative & support | 2019 |
| Aluter Ltd | Manufacturing | 2020 |
| Alvami Ltd | Hospitality | 2020 |
| Alvaraka Limited | Hospitality | 2023 |
| Alveint Ltd | Education | 2025 |
| Alvilix Ltd | Wholesale & retail | 2025 |
| Alvornex Ltd | Wholesale & retail | 2026 |
| Alwakeelinterprises Ltd | Wholesale & retail | 2025 |
| Alwanga Master Ltd | Wholesale & retail | 2026 |
| Always Online Limited | Professional & scientific | 2020 |
| Alx&Ran Automotive Limited | Professional & scientific | 2015 |
| ALY2016 Ltd | Transport & logistics | 2017 |
| Alyana UK Ltd | Administrative & support | 2022 |
| Alytrading Ltd | Wholesale & retail | 2020 |
| Alyxshop Ltd | Wholesale & retail | 2025 |
| Alza Corporation Services Ltd | Information & communication | 2020 |
| Alzaha Ltd | Hospitality | 2018 |
| Alzahid Travel Ltd | Transport & logistics | 2026 |
| Alzain Medical Ltd | Health & social care | 2023 |
| AM & Sons Carpentry Limited | Construction | 2025 |
| AM Apartments Limited | Wholesale & retail | 2025 |
| AM Bristol Electrical Services Ltd. | Construction | 2013 |
| AM Clearance Ltd | Transport & logistics | 2023 |
| AM Coaching and Consultancy Ltd | Health & social care | 2026 |