| Air X Developments Ltd | Construction | 2022 |
| Airam 280 Limited | Health & social care | 2025 |
| Aircraftmaterialsuk.Com Limited | Wholesale & retail | 2001 |
| Airflow Developments Limited | Manufacturing | 1955 |
| Airpart Supply Limited | Wholesale & retail | 1984 |
| Airpool Limited | Professional & scientific | 2019 |
| Airport to Home 247 Heathrow Taxi Ltd | Transport & logistics | 2023 |
| Airportsuktravel Limited | Other services | 2014 |
| Airspares Limited | Extraterritorial | 2007 |
| Airways Homes Limited | Real estate | 1964 |
| Aisar Management Ltd | Real estate | 2024 |
| Aisha Property Limited | Households | 2013 |
| Aisha Spice Ltd | Hospitality | 2022 |
| Aishaz Marketing Services Ltd | Professional & scientific | 2018 |
| AIX Ltd | Professional & scientific | 2025 |
| AJ Cleaning Services (UK) Limited | Administrative & support | 2012 |
| AJ Dilan Limited | Wholesale & retail | 2022 |
| AJ Foods London Limited | Hospitality | 2024 |
| AJ Optics Limited | Health & social care | 2014 |
| AJ Wiring Ltd | Information & communication | 2016 |
| AJA Enterprise Services Limited | Administrative & support | 2017 |
| AJA Fashions Limited | Wholesale & retail | 2026 |
| Ajex Global Ltd | Wholesale & retail | 2024 |
| Ajfd Limited | Information & communication | 2019 |
| AJJ Enterprises Limited | Real estate | 2019 |
| AJK Autos Ltd | Wholesale & retail | 2026 |
| AJK Building and Electrics Ltd | Administrative & support | 2011 |
| Ajpm Services Limited | Professional & scientific | 2017 |
| AJQ Property Ltd | Real estate | 2021 |
| AJV Limited | Wholesale & retail | 2002 |
| AJW Weed Control Limited | Other services | 2003 |
| AK Asset Rentals Ltd | Real estate | 2025 |
| AK Development Projects Ltd | Construction | 2018 |
| AK Legacy Builders Ltd | Construction | 2025 |
| AK Motor Group Ltd | Wholesale & retail | 2024 |
| AK Property Services Limited | Real estate | 2025 |
| Akai Properties Ltd | Real estate | 2022 |
| Akazai Express Ltd | Transport & logistics | 2026 |
| Akbas Engineering Limited | Professional & scientific | 2025 |
| AKH Advisory Ltd | Professional & scientific | 2024 |
| Akhtar Services Limited | Health & social care | 2024 |
| Akhtarz Limited | Hospitality | 2024 |
| Akms IT Solutions Ltd | Information & communication | 2010 |
| Akrams Catering & Event Management Limited | Hospitality | 2012 |
| Akruti Consulting Ltd | Information & communication | 2013 |
| Aks(Uk) Limited | Real estate | 2019 |
| Aktimon Limited | Real estate | 2007 |
| AL Aslam Motor Import & Export Limited | Wholesale & retail | 2013 |
| AL Madina Sweets Ltd | Hospitality | 2025 |
| AL Mush Limited | Hospitality | 2025 |
| AL Rizq Supermarket Ltd | Wholesale & retail | 2023 |
| AL Watan Supermarkets Ltd | Wholesale & retail | 2020 |
| Al-Baqir Community Centre Ltd | Education | 2019 |
| Al-Fareed Clothing Limited | Wholesale & retail | 2024 |
| Al-Fattah Taxwise Ltd | Professional & scientific | 2025 |
| Al-Pha-X Ltd | Information & communication | 2019 |
| Al-Shifa Trading Ltd | Wholesale & retail | 2006 |
| Alan Spargo Limited | Manufacturing | 1975 |
| Alan&Stefy Ltd | Transport & logistics | 2020 |
| Alanjo Limited | Wholesale & retail | 2003 |
| Alaska TV Productions Limited | Information & communication | 2010 |
| ALB Traffic Management Ltd | Construction | 2022 |
| Albex Ltd | Professional & scientific | 2015 |
| Albion Support Group Ltd | Administrative & support | 2025 |
| Alck Electrical Solutions Limited | Other services | 2019 |
| Alethaimassage Ltd | Other services | 2024 |
| Alevia Health Care Ltd | Health & social care | 2010 |
| Alex Luxdeco Ltd | Construction | 2021 |
| Alex Shadow Ltd | Administrative & support | 2025 |
| Alex's Decorating Limited | Construction | 2025 |
| Alexander Court Ltd | Households | 2017 |
| Alexander Services Limited | Administrative & support | 1993 |
| Alexander Systems Limited | Construction | 2001 |
| Alexo Fleets Limited | Transport & logistics | 2025 |
| Alfa Constructions Birmingham Limited | Construction | 2025 |
| Alfa Home Extensions Ltd | Construction | 2020 |
| Alferdo Trading Company Limited | Wholesale & retail | 2023 |
| Alfie Marketing Ltd | Professional & scientific | 2019 |
| Alfred Recruitment LLP | | 2015 |
| Algreta Solutions Limited | Wholesale & retail | 2004 |
| Alhada Limited | Wholesale & retail | 2021 |
| ALI & Co Holdings Ltd | Financial services | 2026 |
| ALI Aesthetics MD Ltd | Health & social care | 2023 |
| ALI Akbar Property Company Limited | Real estate | 2022 |
| ALI Braid Limited | Administrative & support | 2016 |
| ALI Dennett Ltd | Professional & scientific | 2025 |
| ALI Lewinton Interiors Limited | Professional & scientific | 2004 |
| ALI Motors 123 Ltd | Wholesale & retail | 2018 |
| ALI Multilateral Services Ltd | Professional & scientific | 2011 |
| Alibi Properties Ltd | Real estate | 2020 |
| Align Consulting Limited | Administrative & support | 2021 |
| Aligna Wellness Ltd | Information & communication | 2025 |
| Alignflow Ltd | Professional & scientific | 2023 |
| Alina Travel Ltd | Administrative & support | 2011 |
| Alison a Downie Key Wind Music Ltd | Education | 2016 |
| Alison Education UK Ltd | Education | 2023 |
| ALJ Assembly Limited | Manufacturing | 2003 |
| ALK Cleaning Limited | Administrative & support | 2017 |
| Alkasun Limited | Professional & scientific | 2021 |
| ALL Access Healthcare Group Ltd | Health & social care | 2019 |