| Ahbg Financial Planning Limited | Financial services | 2025 |
| Ahenny Limited | Other services | 2016 |
| AHK Property Limited | Administrative & support | 2016 |
| Ahoyhoy Ltd | Professional & scientific | 2015 |
| AHS Installations Ltd | Construction | 2010 |
| Ahsan Express Limited | Hospitality | 2026 |
| AI 452B Ltd | Other services | 2023 |
| AI Adventures Ltd | Education | 2019 |
| AI Digitals Group Ltd | Information & communication | 2024 |
| AI Forensics Limited | Financial services | 2023 |
| AI Hotel Limited | Hospitality | 2024 |
| AI Marketer Ltd | Professional & scientific | 2025 |
| AI Mungo Limited | Professional & scientific | 2023 |
| Ai-Em Ltd | Information & communication | 2008 |
| AID Hospitality Ltd | Hospitality | 2021 |
| AID Properties Ltd | Financial services | 2024 |
| Aiden Barber Salon Ltd | Other services | 2025 |
| Aiforce Ltd | Information & communication | 2019 |
| Aigentifyable Ltd | Information & communication | 2026 |
| Aikona Media Ltd | Information & communication | 2025 |
| Ailish Ltd | Hospitality | 2023 |
| AIM High Lifestyle Ltd | Manufacturing | 2018 |
| Ainsworth Kitchens Ltd | Construction | 2025 |
| Aion Corporate Finance Limited | Professional & scientific | 2009 |
| Aion Gaming Ltd | Professional & scientific | 2025 |
| AIP Heritage Ltd | Arts & recreation | 2025 |
| Air Home Lets Ltd | Real estate | 2018 |
| Air Hugs Design Limited | Administrative & support | 2008 |
| Air Quality Experts Ltd | Professional & scientific | 2024 |
| Air Spring Limited | Wholesale & retail | 2012 |
| Air Street Store Limited | Wholesale & retail | 2015 |
| Air Supply Consulting Ltd | Professional & scientific | 2021 |
| Airbot Technology Limited | Information & communication | 2016 |
| Aircraft Ltd | Transport & logistics | 2021 |
| Airflow Installations Limited | Construction | 2011 |
| Airlineprep Limited | Transport & logistics | 2016 |
| Airmid Medical Consultancy Limited | Health & social care | 2025 |
| Airnex Climate Solutions Ltd | Energy | 2026 |
| Airware Solutions Limited | Information & communication | 2021 |
| Aisolve Limited | Information & communication | 2007 |
| Aitransformers Ltd | Information & communication | 2024 |
| AIU Studio Ltd | Arts & recreation | 2019 |
| AJ Brighton Limited | Health & social care | 2021 |
| AJ Brown Roof Seal and Property Services Ltd | Construction | 2026 |
| AJ Exclusive Events Ltd | Education | 2014 |
| AJ Healthcare Services Limited | Health & social care | 2016 |
| AJ Shoreprint Limited | Manufacturing | 2002 |
| AJ Short Electrical Limited | Construction | 2022 |
| Aj's Seasoned Caterers Ltd | Hospitality | 2017 |
| AJ2 Asset Management Ltd | Financial services | 2024 |
| AJA Fabrications Ltd | Manufacturing | 2009 |
| AJA Propertiesuk Limited | Real estate | 2017 |
| AJB Global Holdings Limited | Financial services | 2025 |
| AJB Homes Limited | Real estate | 2025 |
| Ajb.Fitness Limited | Arts & recreation | 2025 |
| AJC Holdings Limited | Professional & scientific | 2000 |
| AJG Welding Ltd | Manufacturing | 2023 |
| AJH Decorating Ltd | Construction | 2018 |
| AJH London Ltd | Information & communication | 2018 |
| AJI Productions Limited | Information & communication | 2021 |
| Ajjr Commercial Ltd | Wholesale & retail | 2026 |
| AJL Sussex Ltd | Other services | 2025 |
| AJP Interactive Limited | Information & communication | 2023 |
| AJQ Housing Solutions Ltd | Professional & scientific | 2025 |
| AJR Renovate & Build Ltd | Construction | 2022 |
| AJS UK Group Limited | Financial services | 2020 |
| Ajston Consulting Ltd | Professional & scientific | 2009 |
| AJT Managed IT Services Ltd | Information & communication | 2019 |
| AJW Power Limited | Professional & scientific | 2022 |
| AJW Property Management and Maintenance Ltd | Households | 2019 |
| AJW Software Consulting Limited | Information & communication | 2014 |
| AKA Construction & Cleaning Ltd | Construction | 2026 |
| AKC Holdings Limited | Financial services | 2012 |
| AKC Systems Limited | Wholesale & retail | 1997 |
| Akerolabs Limited | Information & communication | 2019 |
| AKF Wellness Limited | Wholesale & retail | 2023 |
| Akimbo Theatre Ltd | Arts & recreation | 2021 |
| Akin Industries Ltd | Arts & recreation | 2006 |
| Akissi Cleaning Limited | Manufacturing | 2026 |
| Akmj Holdings Ltd | Financial services | 2019 |
| AKQ Design Limited | Administrative & support | 2008 |
| Akrm Ltd | Transport & logistics | 2022 |
| Akrs (Holdings) Limited | Health & social care | 2012 |
| Aktineum Limited | Professional & scientific | 2024 |
| Akuko Ltd | Information & communication | 2022 |
| AL Badawi Group Ltd | Wholesale & retail | 2023 |
| AL Duomo Ltd | Hospitality | 2020 |
| AL Duomo Occupancy Ltd | Real estate | 2020 |
| AL Fish and Chips Ltd | Hospitality | 2025 |
| AL Medinah MDR Ltd | Other services | 2026 |
| AL Radiology Ltd | Health & social care | 2023 |
| Al-Andulas Gate Ltd | Other services | 2019 |
| Aladdin's Jewellery Work Shop Ltd | Other services | 2024 |
| Alali Osman Ltd | Hospitality | 2020 |
| Alan Clark Homes Limited | Real estate | 2002 |
| Alan Haddow Limited | Administrative & support | 2008 |
| Alan M. Milne Ltd | Financial services | 2019 |
| Alan Rhodes Associates Ltd | Administrative & support | 2000 |
| Alannah Limited | Professional & scientific | 2014 |
| Alara Cosmetics Limited | Wholesale & retail | 2025 |