| Amorad UK Limited | Professional & scientific | 2019 |
| Ample Energy Special Projects Ltd | Construction | 2024 |
| Ample Security Limited | Administrative & support | 2019 |
| AMS Building & Construction Limited | Construction | 2025 |
| AMV Logistics Ltd | Transport & logistics | 2019 |
| Anchor & Key Realty Ltd | Real estate | 2025 |
| Anclar Ltd | Administrative & support | 2017 |
| Anderson Jones Limited | Construction | 2020 |
| Andrei Florin Zamfir Ltd | Construction | 2026 |
| Andrei Ludovic Zamfir Ltd | Transport & logistics | 2026 |
| Angel Healthcare (Support) Ltd | Health & social care | 2026 |
| Angel Healthcare Professionals Ltd | Health & social care | 2016 |
| Angeldriver Services Limited | Transport & logistics | 2019 |
| Angelic Love Ltd | Wholesale & retail | 2020 |
| Angelo Biotech International UK Ltd | Wholesale & retail | 2024 |
| Angels Abode Limited | Real estate | 2007 |
| Angels Catering and Events Ltd | Hospitality | 2020 |
| Anil KUMAR2 Ltd | Construction | 2025 |
| Annamegan Ltd | Manufacturing | 2020 |
| Anngrove Services Ltd | Professional & scientific | 2020 |
| Anode & Cathode Ltd. | Wholesale & retail | 2018 |
| Another Step UP Ltd | Education | 2019 |
| ANR Group of Companies Limited | Hospitality | 2025 |
| Antelope Group Ltd | Other services | 2025 |
| Anthony Kings Estates Limited | Real estate | 2015 |
| Anthony Martin Estate Agents (North Kent) Limited | Real estate | 2016 |
| Anto and Alex Ltd. | Administrative & support | 2019 |
| Antvalvic Limited | Health & social care | 2025 |
| Aosq Ltd | Hospitality | 2026 |
| Aosq Property & Facilities Ltd | Real estate | 2023 |
| Apex 2000 (UK) Limited | Construction | 2007 |
| Apex Experts Roofing & Building Ltd | Construction | 2025 |
| APJ Kitchens Ltd | Construction | 2018 |
| APJ Services (London) Ltd | Professional & scientific | 2018 |
| Aplusm Care Group Ltd | Health & social care | 2024 |
| Apna Foods Ltd | Wholesale & retail | 2026 |
| APO Consulting Ltd | Professional & scientific | 2014 |
| Apostu Services Ltd | Transport & logistics | 2015 |
| Applewood Construction (Ashford) Ltd | Construction | 2017 |
| Applewood Construction Kent Limited | Construction | 2014 |
| Applewood Fencing Ltd | Wholesale & retail | 2017 |
| Applewood Holdings(Kent) Ltd | Financial services | 2018 |
| Appliance Ltd | Health & social care | 2013 |
| Apto Initiatives CIC | Other services | 2021 |
| Aqilabs Ltd | Information & communication | 2025 |
| Aqua DRY Cleaners Ltd | Other services | 2018 |
| Aqua Sixteen Limited | Transport & logistics | 2019 |
| Arcane Properties Ltd | Real estate | 2023 |
| Arch Brick Limited | Administrative & support | 2020 |
| Archer Daniels Midland Erith Limited | Manufacturing | 1919 |
| Ardentine Ltd | Hospitality | 2026 |
| Areg & Co Limited | Health & social care | 2018 |
| Arham International Ltd | Wholesale & retail | 2026 |
| Aries Property Solutions Ltd | Real estate | 2023 |
| ARK Wholesalers Limited | Wholesale & retail | 2022 |
| Armat Trade and Service Ltd | Wholesale & retail | 2010 |
| Armazi Ltd | Professional & scientific | 2018 |
| Armonyx Ltd | Construction | 2022 |
| Aroma Baristas Ltd | Hospitality | 2008 |
| Arris Construction Ltd | Construction | 2024 |
| Arsh Construction London Ltd | Construction | 2023 |
| Arsh Heating Limited | Construction | 2014 |
| Art TIM Spedition Ltd | Transport & logistics | 2019 |
| Arthur Morrison Ltd | Manufacturing | 2017 |
| Arthur Morrison Property Ltd | Households | 2009 |
| Aryxx Ltd | Wholesale & retail | 2025 |
| ASC Flooring and Screeding Ltd | Construction | 2017 |
| Ascendance Investments & Properties Ltd | Financial services | 2021 |
| ASK Group (Trading AS Thornton Heath After School Club) Limited | Education | 2025 |
| ASK I'M Listening Limited | Health & social care | 2025 |
| ASK Recruitment Education Services Ltd | Administrative & support | 2025 |
| Aslam Group Limited | Wholesale & retail | 2024 |
| Aslan Pharmaceutical and Healthcare Ltd | Wholesale & retail | 2025 |
| Aslan Recruitment Ltd | Administrative & support | 2021 |
| Aspire Edge Capital Limited | Real estate | 2025 |
| Aspire Home Estate Ltd | Real estate | 2024 |
| ASQ Solutions Limited | Education | 2024 |
| Asquared Living Ltd | Hospitality | 2026 |
| Atanak Forwarding Limited | Transport & logistics | 2002 |
| Atheethan Trading Ltd | Hospitality | 2025 |
| Atherall Site Solutions Ltd | Construction | 2016 |
| Atlas Haulage Solutions Ltd | Transport & logistics | 2025 |
| Atlas Motor Group Ltd | Wholesale & retail | 2025 |
| Atmj Ltd | Information & communication | 2021 |
| ATS Investment Ltd | Real estate | 2013 |
| ATT Afrigrowth Marketing Ltd | Information & communication | 2026 |
| Attsport Developments Ltd | Other services | 2022 |
| Atuobeng Solutions Limited | Professional & scientific | 2021 |
| Audacious Property Investment Ltd | Financial services | 2026 |
| Audric Kanyinda Ltd | Real estate | 2021 |
| Austin Family Haulage Ltd | Transport & logistics | 2013 |
| Autera Technologies Ltd | Information & communication | 2025 |
| AUTHENTIC1 Limited | Construction | 2015 |
| Autism Gifted Hands Limited | Health & social care | 2019 |
| Avanti Maintenance Services Ltd | Construction | 2023 |
| Avaron Graphics Limited | Administrative & support | 2015 |
| Avenue Road Bowls Club Limited | Arts & recreation | 2005 |
| Avery Joinery Ltd | Construction | 2023 |
| Aviella Ltd | Health & social care | 2016 |
| Aviella-Uk Ltd | Other services | 2025 |