| Alaren Machine Hire Ltd | Wholesale & retail | 2024 |
| Alboney Limited | Extraterritorial | 2022 |
| Alder Sage Limited | Real estate | 2024 |
| Alexander Brian Rouse Ltd | Extraterritorial | 2022 |
| Alixei Haulage Limited | Construction | 2018 |
| Aliya Trading Ltd | Hospitality | 2023 |
| ALL Ebikes.Co.Uk Ltd | Wholesale & retail | 2021 |
| ALL Star Cars and Vans Limited | Wholesale & retail | 2025 |
| ALL Talent Solutions Ltd | Administrative & support | 2025 |
| ALL4EXPORT Limited | Wholesale & retail | 2018 |
| Allcoat Decorating Ltd | Construction | 2022 |
| Allez Accounting Ltd | Professional & scientific | 2023 |
| Allpa Wira Trading UK Limited | Wholesale & retail | 2019 |
| Allspecs Ltd | Wholesale & retail | 2010 |
| Alston Estates Ltd | Real estate | 2025 |
| Alstons Autos Ltd | Wholesale & retail | 2020 |
| Alstons Developments Limited | Construction | 2022 |
| Aluminium by Design Limited | Manufacturing | 1995 |
| Always Graftin Transport Limited | Transport & logistics | 2016 |
| AM Hydraulic Services Limited | Professional & scientific | 2020 |
| AMA Financial Services Limited | Financial services | 2021 |
| Amazing Grace Medicals Limited | Professional & scientific | 2014 |
| Amazing Homes Limited | Real estate | 2008 |
| Amazing Promotional Merchandise Limited | Wholesale & retail | 2003 |
| Ambiente FM Ltd | Administrative & support | 2017 |
| AME Motor Services Limited | Wholesale & retail | 2026 |
| Amec Plumbing & Heating Limited | Construction | 2022 |
| AMS Hishtadles Ltd | Real estate | 2026 |
| Andrews - Jeakins Ltd | Other services | 2025 |
| Andy J Hardwick Limited | Professional & scientific | 2026 |
| Andys Property Solutions Limited | Administrative & support | 2018 |
| Angel Design & Build Ltd | Other services | 2013 |
| Angel Wigs Ltd | Other services | 2008 |
| Anglian Contracts Limited | Other services | 2019 |
| Angus BUS Company Limited | Transport & logistics | 2024 |
| Annie’S Bakes Ltd | Hospitality | 2025 |
| Anthony Quirk (East) Limited | Real estate | 2008 |
| Anto Sharp Ltd | Construction | 2016 |
| ANW Associates London Limited | Wholesale & retail | 2012 |
| ANW Properties London Limited | Real estate | 2019 |
| AO Logistics Services Ltd | Transport & logistics | 2024 |
| Apex Aerials Limited | Administrative & support | 2008 |
| APJ Consultancy Limited | Financial services | 2024 |
| Apna Property Limited | Real estate | 2019 |
| Apollo Contracts Ltd | Construction | 2024 |
| Appointway Limited | Administrative & support | 1993 |
| Aptmad Ltd | Health & social care | 2015 |
| Aqualib Ventures Limited | Other services | 2009 |
| Aquaponix Limited | Wholesale & retail | 2015 |
| Aquatech Holdings Limited | Financial services | 2008 |
| AQUATICS2U Ltd | Wholesale & retail | 2017 |
| Aquentis Limited | Construction | 2000 |
| ARA Eximium Ltd | Other services | 2014 |
| Archibeats CIC | Information & communication | 2023 |
| AREA2 Facilities Management Ltd | Construction | 2022 |
| Aries Packaging Limited | Manufacturing | 2024 |
| Arise Plus Company Limited | Administrative & support | 2026 |
| Arnies Pet Services Limited | Wholesale & retail | 2018 |
| Artfix Maintenance Ltd | Manufacturing | 2020 |
| Artois International S.A. Ltd | Financial services | 2020 |
| Artquarters Press Limited | Other services | 2010 |
| Asbes Limited | Construction | 2008 |
| ASC Project Services Ltd | Administrative & support | 2009 |
| Ascend Facilities Limited | Administrative & support | 2016 |
| Ascending R&C Ltd | Health & social care | 2024 |
| ASH Building Services London Ltd | Construction | 2018 |
| Ashley Plant Limited | Administrative & support | 2007 |
| Ashway Estates Ltd | Real estate | 2018 |
| Ash’S Fruits Ltd | Wholesale & retail | 2025 |
| Asia Food Products Co. Limited | Manufacturing | 1971 |
| Asip Limited | Hospitality | 2011 |
| ASP Classics Ltd | Administrative & support | 2022 |
| Aspegio Ltd | Professional & scientific | 2021 |
| Aspire Workplace Training Limited | Education | 2021 |
| Asset Assure Limited | Other services | 2015 |
| Assured Care Personnel Ltd | Extraterritorial | 2017 |
| Asteria Aerialwear Ltd | Wholesale & retail | 2021 |
| Astute HOG Limited | Information & communication | 2013 |
| AT Home and Property Ltd | Real estate | 2024 |
| Atos Consultancy Limited | Information & communication | 2011 |
| Atws (Training & Competence) Ltd. | Administrative & support | 2002 |
| Aumlink Ltd | Professional & scientific | 2020 |
| Austika Trends Limited | Wholesale & retail | 2026 |
| Austin Matthews Group Ltd | Construction | 2015 |
| Auto Spares (Canvey Island) Limited | Wholesale & retail | 2014 |
| Autofly Ltd | Administrative & support | 2025 |
| Automotive Business Solutions Limited | Other services | 2025 |
| Automotive Production Technologies Limited | Manufacturing | 1988 |
| Autopia Control and Automation Solutions Limited | Manufacturing | 2015 |
| Autoview Windscreens Essex Ltd | Wholesale & retail | 2018 |
| Avail Optics Ltd | Wholesale & retail | 2020 |
| Avidbold Limited | Administrative & support | 1999 |
| Avidgilt Limited | Real estate | 1993 |
| Avoa Plumbing Ltd | Construction | 2017 |
| Avodas Hatfilah Ltd | Other services | 2023 |
| AVW Associates Limited | Financial services | 2026 |
| AYA Design Studio Ltd | Administrative & support | 2021 |
| Ayay Limited | Hospitality | 2025 |
| Aytos Homes Ltd | Real estate | 2019 |
| AZI Limited | Professional & scientific | 2024 |