| AM Living Ltd | Wholesale & retail | 2025 |
| Amaar Akbar Boxing Ltd | Arts & recreation | 2020 |
| Amaj Limited | Real estate | 2017 |
| Amal Marketing Ltd | Information & communication | 2023 |
| Aman & Tsalach Enterprise Ltd | Health & social care | 2015 |
| Amani North East Limited | Wholesale & retail | 2026 |
| Amani Yorkshire Limited | Wholesale & retail | 2026 |
| Amare Living UK Limited | Wholesale & retail | 2025 |
| Amaze Training Ltd | Administrative & support | 2010 |
| Amber Elite Estate Ltd | Real estate | 2026 |
| AMG Engineering Supplies (Holdings) Limited | Financial services | 2023 |
| AMG Engineering Supplies (Investments) Limited | Financial services | 2023 |
| AMG Engineering Supplies Ltd | Manufacturing | 2012 |
| Amira London Fashion Ltd | Wholesale & retail | 2019 |
| Ammie Foods Ltd | Hospitality | 2025 |
| Amorini Furniture Ltd | Wholesale & retail | 2022 |
| Ample Fashions Ltd | Professional & scientific | 2024 |
| Ampsbuild Ltd | Construction | 2025 |
| AMX Supplies Ltd | Wholesale & retail | 2025 |
| AMZ Consultant Group Ltd | Financial services | 2026 |
| Anas Travels Ltd | Transport & logistics | 2026 |
| ANASA24 Ltd | Wholesale & retail | 2023 |
| Andani & Co Ltd | Real estate | 2025 |
| Andani Global Development Initiative | Health & social care | 2025 |
| Anderson Commercial Services Ltd | Wholesale & retail | 2023 |
| Anderson Sakaria Investments Ltd. | Real estate | 2018 |
| Anderson Site Services Limited | Construction | 2024 |
| Andrew Edgar Transport Ltd | Transport & logistics | 2019 |
| ANE3QA Ltd | Health & social care | 2022 |
| Aneseldo Ltd | Transport & logistics | 2018 |
| Angel Property Services Ltd | Hospitality | 2021 |
| Anglofull Limited | Hospitality | 2000 |
| Anim Optics Ltd | Health & social care | 2023 |
| Anjum Fabrics Ltd | Wholesale & retail | 2025 |
| ANN Thomas Limited | Wholesale & retail | 2008 |
| ANT Investment Group Limited | Financial services | 2025 |
| Anvitech Ltd | Construction | 2019 |
| Anza Delights Limited | Wholesale & retail | 2026 |
| Apeiro Recruitment Limited | Administrative & support | 2023 |
| Apex Furniture Ltd | Manufacturing | 2019 |
| Apex I.C.T UK Ltd | Wholesale & retail | 2022 |
| Apni Investment Ltd | Real estate | 2020 |
| Apollo Batley Holdings Limited | Financial services | 2023 |
| Apollo Beds Limited | Manufacturing | 1996 |
| Appcheck Limited | Information & communication | 2009 |
| Apporatech Publishing Ltd | Information & communication | 2026 |
| Aqas Healthcare Limited | Health & social care | 2020 |
| Aqua Interpreting Solutions Ltd | Professional & scientific | 2014 |
| Aqua Languages Limited | Professional & scientific | 2013 |
| Aquarium Direct Ltd | Hospitality | 2014 |
| Aquazone (UK) Limited | Wholesale & retail | 2008 |
| Archibold Beckers Beds Ltd | Manufacturing | 2018 |
| Archibold Beckers Investments Ltd | Real estate | 2022 |
| Archibolds Beds Limited | Manufacturing | 2022 |
| Aremzi Properties Ltd | Real estate | 2024 |
| Argent Care Limited | Health & social care | 2020 |
| ARH Mart Ltd | Wholesale & retail | 2022 |
| Armitage Sales Ltd | Real estate | 2015 |
| Artistry Academy Ltd | Other services | 2019 |
| Artura International Ltd | Other services | 2025 |
| Arushan Limited | Real estate | 2026 |
| AS Modern Decorating Ltd | Construction | 2024 |
| AS Neuro Ltd | Health & social care | 2024 |
| Asad MIR Locums Ltd | Health & social care | 2016 |
| Asad MIR Properties Ltd | Real estate | 2026 |
| ASB Electrical Supplies Ltd | Wholesale & retail | 2022 |
| ASB Holdings Group Ltd | Real estate | 2024 |
| ASF Research Ltd | Real estate | 2020 |
| ASG Associates Limited | Professional & scientific | 2004 |
| ASG Financial Solutions Ltd | Administrative & support | 2015 |
| ASH Business Solutions Ltd | Health & social care | 2026 |
| Ashed Private Limited | Health & social care | 2019 |
| Asher Essa Ltd | Transport & logistics | 2023 |
| Ashlea Developments Limited | Construction | 2016 |
| Ashwells Legal Limited | Real estate | 2025 |
| Asiphande Ltd | Health & social care | 2024 |
| ASK Building Control Ltd | Administrative & support | 2012 |
| ASN Production & Logistics Ltd | Manufacturing | 2023 |
| Aspfm Limited | Professional & scientific | 2022 |
| Aspire Sports Resolution Ltd | Education | 2015 |
| Asptfm Limited | Professional & scientific | 2022 |
| Assetcool Limited | Manufacturing | 2020 |
| Astill Site Services Ltd | Manufacturing | 2021 |
| Astir Hub Ltd | Hospitality | 2023 |
| Astrada Solutions Ltd | Other services | 2018 |
| ASZ DIY Ltd | Wholesale & retail | 2025 |
| ASZ Yorkshire Ltd | Real estate | 2025 |
| Athena (UK) Limited | Professional & scientific | 2014 |
| Athena Haulage Ltd. | Construction | 2015 |
| Athena Plant Limited | Construction | 2008 |
| Atlantic GAS and Power Ltd | Administrative & support | 2017 |
| Atlas Business Consultants Ltd | Professional & scientific | 2021 |
| Atlas Enterprises (Leeds) Limited | Real estate | 2009 |
| Atlas Green Holdings Ltd | Financial services | 2013 |
| Atlas Green Limited | Administrative & support | 2003 |
| ATM Invest Limited | Real estate | 2024 |
| Atomic Sleep Ltd | Manufacturing | 2021 |
| ATZ Developments Ltd | Real estate | 2017 |
| AU Gold Beds Ltd | Manufacturing | 2020 |
| AU Luxury Estates Ltd | Real estate | 2023 |